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Building a socket 7 pc from scratch

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First post, by tanasen

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Hey everyone. I have no experience in socket 7 machines and I'm trying to find ways to build one on the cheap. About a couple months ago I found a socket 7 motherboard. It is a Soyo SY-5EAS and came with a Pentium MMX 200Mhz cpu and 2 sticks of EDO ram (32mb total I guess). The chipset of the board is from ETEQ; it's the EQ82C6618 which is perhaps a different name for the VIA Apollo VPX chipset.
My plan is to use this machine as a platform for a Voodoo1-Riva 128 combo, as I own both cards. For the OS I plan on using DOS 6.22 and Windows95 OSR2 (for the usb support). For storage and drives I'll be getting an SD card to IDE adapter (with a 16gb or maybe a 32gb card), a floppy emulator and a standard IDE Cd-rom drive.

My main concerns are:
1) I cannot test this motherboard yet, unless I can find an AT psu or an AT power adapter for ATX psu's. I have one spare ATX psu for testing (a Seasonic SS-145SFC in perfect working condition). I have found several of these adapters on ebay, but I'd like to hear your recommendations.

2) The board comes with an AT keyboard connector, so I guess I'll be alright with a simple AT to PS/2 adapter, as I cannot find any AT keyboards.

3) The board has a six pin input for a PS/2 mouse connector but I can't find anything on ebay. I'm pretty sure that this https://www.ebay.com/itm/2Pcs-PS2-Jack-Mouse- … P0AAOSwcUBYIZYH is not what I'm looking for cause I need a female connector.

4) Same goes for the USB connector. The board has a ten pin input. I found this on ebay https://www.ebay.com/itm/Motherboard-9-10Pin- … REAAOSwElpas4EO but I'm not sure because I don't think the board supports USB 2.0 and I cannot find a USB 1.0 connector.

5) I don't have an I/O shield. Cannot find one for this board. Hope to find a shielded AT case.

6) For sound, I'm looking into some good but cheap ISA cards, like the ES1868F which has excellent FM sound and good compatibilty.

I know I could just buy a good working pc from that era and modify it to my needs as I have done in the past, but this time I'd like to do it from scratch. Any other recommendations are welcome. Cheers!

PC1😜 III-S 1.4GHz, GA-6VTXE, 512MB SDRAM, Albatron FX5900XTV 128MB, SB Live! 5.1
PC2😜 III 800MHz, MS-6178, 256MB SDRAM, 3DFX Voodoo3 2000 PCI, Creative CT4810
PC3😜 MMX 200MHz, SY-5EAS5, 128MB SDRAM, Diamond Monster 3D, Diamond Viper V330, ESS 1868F

Reply 1 of 22, by jheronimus

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My plan is to use this machine as a platform for a Voodoo1-Riva 128 combo, as I own both cards. For the OS I plan on using DOS 6.22 and Windows95 OSR2 (for the usb support). For storage and drives I'll be getting an SD card to IDE adapter (with a 16gb or maybe a 32gb card), a floppy emulator and a standard IDE Cd-rom drive.

I don't think you need a separate DOS 6.22 installation. Pure DOS does not support FAT32, so it won't be able to properly work with the partition that you'll have Windows 95 on. You can just use FAT16, but that means that you can't have partitions larger that 2GB.

Generally DOS 7.1 (the one Win9x is built upon) does not have any compatibility issues, you just have to make sure to configure stuff like mouse, sound and optical drives under DOS — there's a lot of documentation online about this.

3) The board has a six pin input for a PS/2 mouse connector but I can't find anything on ebay. I'm pretty sure that this https://www.ebay.com/itm/2Pcs-PS2-Jack-Mouse- … P0AAOSwcUBYIZYH is not what I'm looking for cause I need a female connector.

Yes, that looks like a connector that should be soldered onto an ATX board. I think you need something like this.

In my experience, most Pentium motherboards have the same pinout for PS/2 connectors. I've seen only three exceptions: an Intel Batman's Revenge (Socket 4), most Asus boards (they have a combined PS/2+USB+IR header) and my Lucky Star 5MVP3 board. So you might have a non-standard pinout, but it's highly unlikely. And these PS/2 panels tend to be really cheap, so just give it a try.

Alternatively — just find a COM port mouse.

4) Same goes for the USB connector. The board has a ten pin input. I found this on ebay https://www.ebay.com/itm/Motherboard-9-10Pin- … REAAOSwElpas4EO but I'm not sure because I don't think the board supports USB 2.0 and I cannot find a USB 1.0 connector.

In two and a half years I've been doing this hobby I've never came across a USB 1.0 port panel. USB 2.0 is pin-compatible, but won't work on a board like yours.

Maybe try a PCI USB controller like this? I have one, but I've never tried it on a Socket 7, so maybe others can comment on this.

5) I don't have an I/O shield. Cannot find one for this board. Hope to find a shielded AT case.

mpe_dk42-3.jpg

AT motherboards don't have I/O shields since they only have one port onboard — the AT keyboard port. If you plan on using this board in ATX case — that's another story. I don't think that anyone ever made a shield with a single AT port cutout, so you might have to make one yourself somehow.

6) For sound, I'm looking into some good but cheap ISA cards, like the ES1868F which has excellent FM sound and good compatibilty.

Yes, as far as SB16 clones go, ESS has a reputation for being the best choice, second to maybe only Yamaha cards.

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Reply 2 of 22, by dionb

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You can use USB2 brackets on USB 1 headers so long as the pinout is the same. Almost all newer headers & brackets use:
5V D- D+ GND NC
5V D- D+ GND KEY/NC

Some older boards however have:
5V D- D+ GND NC
NC GND D+ D- 5V

If you attach a modern header to that, one of the two ports won't work. Workaround is to only attach one side for one port.

Check in the manual what the pinout is before connecting anything to it.

Either way, don't expect much from USB1.0 and Win95OSR3. HID (keyb/mouse) might work, but that's about it. If you want any more, use at least Win98SE - and even there expect fun to get drivers for things like storage working.

One thing you're not clear on is RAM. Up to about 256MB (for Win98SE) more is better, but stay under the cacheable limit of your chipset and motherboard unless you intend to install a K6-2+ or 3(+) CPU with its own L2 cache.

I'm a bit rusty on caching limits of older Via chipsets, but iirc VPX allowed 64MB RAM in Writeback mode or 128MB in Writethrough. If so, that means that 64MB will give you best performance, unless you're running things that need more RAM than that.

As for the sound card, the ESS 1868F sounds fine. Do be aware though that it's an ISA PnP chip, so dependent on PnP implementations of your BIOS and (Win9x) OS. The ESS688F is essentially the same design but without PnP. That needs manual configuration, but at least it's deterministic - if you do it right, it works. Call me an old codger, but I never really trust ISA PnP as the whole PnP thing was still in its infancy back then and implementations were rarely perfect.

Reply 3 of 22, by gdjacobs

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jheronimus wrote:

Yes, as far as SB16 clones go, ESS has a reputation for being the best choice, second to maybe only Yamaha cards.

They trade blows. Yamaha has authentic OPL3, but ESS cards are slightly more compatible with some SB modes.

All hail the Great Capacitor Brand Finder

Reply 4 of 22, by tanasen

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Thanks for your advice, you've been very helpful!

jheronimus wrote:

I don't think you need a separate DOS 6.22 installation. Pure DOS does not support FAT32, so it won't be able to properly work with the partition that you'll have Windows 95 on. You can just use FAT16, but that means that you can't have partitions larger that 2GB.

I remember back in the day they used to do that, but maybe cause they only had small sized hard drives. I could experiment though with a seperate hard drive or sd card. But you're right, I haven't had any issues in Dos 7.1.

jheronimus wrote:

Yes, that looks like a connector that should be soldered onto an ATX board. I think you need something like this.

In my experience, most Pentium motherboards have the same pinout for PS/2 connectors. I've seen only three exceptions: an Intel Batman's Revenge (Socket 4), most Asus boards (they have a combined PS/2+USB+IR header) and my Lucky Star 5MVP3 board. So you might have a non-standard pinout, but it's highly unlikely. And these PS/2 panels tend to be really cheap, so just give it a try.

Alternatively — just find a COM port mouse.

Yes that's exactly what I was looking for.

If I find a COM port mouse can I just plug it in from the sound card?

About the USB support I might as well do my data transfers through the floppy sd emulator, rather than using an add-on card. This motherboard has only 3 PCI slots and I want to leave one for a network card.

I'd better start doing some serious research on AT cases cause they're extremely rare. I guess ATX is out of the question for socket 7.

PC1😜 III-S 1.4GHz, GA-6VTXE, 512MB SDRAM, Albatron FX5900XTV 128MB, SB Live! 5.1
PC2😜 III 800MHz, MS-6178, 256MB SDRAM, 3DFX Voodoo3 2000 PCI, Creative CT4810
PC3😜 MMX 200MHz, SY-5EAS5, 128MB SDRAM, Diamond Monster 3D, Diamond Viper V330, ESS 1868F

Reply 5 of 22, by tanasen

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dionb wrote:
You can use USB2 brackets on USB 1 headers so long as the pinout is the same. Almost all newer headers & brackets use: 5V D- D+ […]
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You can use USB2 brackets on USB 1 headers so long as the pinout is the same. Almost all newer headers & brackets use:
5V D- D+ GND NC
5V D- D+ GND KEY/NC

Some older boards however have:
5V D- D+ GND NC
NC GND D+ D- 5V

If you attach a modern header to that, one of the two ports won't work. Workaround is to only attach one side for one port.

Check in the manual what the pinout is before connecting anything to it.

Either way, don't expect much from USB1.0 and Win95OSR3. HID (keyb/mouse) might work, but that's about it. If you want any more, use at least Win98SE - and even there expect fun to get drivers for things like storage working.

I can't find any info on this in the manual.
Here is a picture of the pinout:
EOuiSbK.jpg

I 've read that you can install the nusb33 driver in OSR2 and have proper usb support. Am I wrong on this?

PC1😜 III-S 1.4GHz, GA-6VTXE, 512MB SDRAM, Albatron FX5900XTV 128MB, SB Live! 5.1
PC2😜 III 800MHz, MS-6178, 256MB SDRAM, 3DFX Voodoo3 2000 PCI, Creative CT4810
PC3😜 MMX 200MHz, SY-5EAS5, 128MB SDRAM, Diamond Monster 3D, Diamond Viper V330, ESS 1868F

Reply 6 of 22, by jheronimus

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tanasen wrote:

If I find a COM port mouse can I just plug it in from the sound card?

No. Soundcards have Gameport with 15 pins, COM port is 9 pins.

You will need to find a COM port panel that plugs into the board — similar to the PS/2 one, but I don't think I've ever heard COM ports to have different pinouts, so it will be easier to find. Or just get any ISA multi I/O card. It looks something like this:

9ENdp35rjjaBb1uU-UM4doExcvWANBQkAB6OXjlyNQDH87wDxsSOlCaEMJI2MQNoMjIPEn90dyAqr41QaPK6cc88RONRMMuJHECFSe7TE2yn1cf8QatyQ5ujPX2ccdVST-btiKR_MjQjvwQEHFSEphS8JBDVH0v0tob2n5K9Gh6WI9DJoqH7sarnYr_Yjk9OxK67D1o8ErQXvpAurB_JzAF-PfjcSi-8gkYy8jOR4V5rlS7pTPsw2LJ44gaEcEllcvgSUQrH3VMcukcX0glYNPlC7whE_koDQiQEbu3EFtfZh-9RGvCVbWyWR3j61ui2b4DAmSoKAIvUkk4FT-8OOSa3Mr2T0JFQnCL3Ace-V0Ggq_SATT5p7_V6SpjIaOmwAQuVnsRUaHx9B_UuPQXraY3P1ANt3UmAvrKkSH0PSQB1gUBkLu8mGzYJT9L-npZTG5LoGeeMtMjPf8QO5spKTrV9YX5e5XzzjaUsPXwRo5_dLVmEgA7iNoDFNm4ng_ETqVoILXke3aUQUogXQdXCxUuTntrd-ogcIHhVx__loOWLLes-zPkYYBQFkzj03N1X-dZYwf2JM7ynE0TINEr-I5pZqg7qRugLGOCWU4UucIx8R92clJcV=w917-h659-no

tanasen wrote:

I'd better start doing some serious research on AT cases cause they're extremely rare. I guess ATX is out of the question for socket 7.

ATX Socket 7 boards actually exist. A lot of late Socket 7 and Super Socket 7 boards came in both AT and ATX flavors. But for some reason nowadays they are rare and expensive compared to AT. Then again, you wouldn't need to bother with PS/2, USB and so on.

However, if I'm not mistaken, it also doesn't mean that you can just use modern ATX power supplies. Supposedly, they don't provide enough power over the 5V rail that some older hardware needs. I've never tried a modern PSU though, just noticed a lot of discussion of 5v rails whenever the topic of ATX comes up.

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Reply 7 of 22, by tanasen

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jheronimus wrote:

However, if I'm not mistaken, it also doesn't mean that you can just use modern ATX power supplies. Supposedly, they don't provide enough power over the 5V rail that some older hardware needs. I've never tried a modern PSU though, just noticed a lot of discussion of 5v rails whenever the topic of ATX comes up.

How much power do I need over the 5V rail for such build? My little seasonic has 14A output on the +5V rail. Is this enough? Also, about the adapter, do I need one with a power switch and -5V conversion?

PC1😜 III-S 1.4GHz, GA-6VTXE, 512MB SDRAM, Albatron FX5900XTV 128MB, SB Live! 5.1
PC2😜 III 800MHz, MS-6178, 256MB SDRAM, 3DFX Voodoo3 2000 PCI, Creative CT4810
PC3😜 MMX 200MHz, SY-5EAS5, 128MB SDRAM, Diamond Monster 3D, Diamond Viper V330, ESS 1868F

Reply 8 of 22, by dionb

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tanasen wrote:
I can't find any info on this in the manual. Here is a picture of the pinout: https://i.imgur.com/EOuiSbK.jpg […]
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I can't find any info on this in the manual.
Here is a picture of the pinout:
EOuiSbK.jpg

That's just the pins, doesn't tell you much about the pinout.

Solution is quite simple really - if you have a Voltage meter. "+5V" is exactly what it sounds like. So if you check the pins one by one measuring between the pin and a known ground, you should find the two +5V pins easily enough. If they're at the same end of the block, you have the new pinout and can just plug in a regular 2x USB bracket. If they're at opposite ends of the block you have the old one and need to somehow turn around half the connector (exactly what options you have depend on the connector itself).

If you don't have a Voltage meter...
1) Get one. Invaluable for hardware diagnostics in any case.
2) Just plug it in and see what happens (not recommended, but +5V is generally not enough to fry anything)
3) use a 5V LED (i.e. HDD LED) and do the same as with the meter. Put the -/GND wire from the LED onto the known ground, use the other one to probe the pins one by one.

I 've read that you can install the nusb33 driver in OSR2 and have proper usb support. Am I wrong on this?

Last time I checked that was Win98SE only, but tbh it's been a very long time since I attempted anything with Win95 and USB, so I might well be wrong.

jheronimus wrote:

[...]

However, if I'm not mistaken, it also doesn't mean that you can just use modern ATX power supplies. Supposedly, they don't provide enough power over the 5V rail that some older hardware needs. I've never tried a modern PSU though, just noticed a lot of discussion of 5v rails whenever the topic of ATX comes up.

Yes and no. Yes, there's discussion, but no, with a board with low requirements like this, almost any modern PSU could handle it easily. You just would need to go overkill on the PSU, which would be hopelessly inefficient.

The discussion is quite simple really: traditionally, the CPU and PCI cards drew their power from the 5V line. When AGP was added to the mix, it drew most of its power from the 3.3V line. So the 12V line was really only used for powering the motors in disk drives and some legacy ISA stuff. That means that in the late 1990s and early 2000s, the 5V line needed by far the most current (even if total power over 12V could be higher), with 3.3V in second place, particularly in the later AGP years. This was the case up to Intel's Pentium 3, but AMD continued down this path with the Socket A platform for a few years more. A typical PSU from this era (like my FSP350-60PN) could deliver 28A on 3.3V, 30A on 5V and only 18A on 12V (note that these currents don't add up to 350W, because no PSU can handle the max current on all lines simultaneously).
The problem here is that delivering a lot of power at low voltage needs lots of thick cables, or the losses mount. When Intel introduced the P4, it knew how much power they would need and realized that getting that out of the 5V line was not a good idea. So they introduced the ATX12V standard, which is the little 2x2 (or in high-end 2x4) yellow and black connector that plugs in to the motherboard next to the CPU. AMD followed suit with the Athlon64. Suddenly the biggest single power user moved from 5V to 12V. That means that power supplies got re-engineered to deliver more power over the 12V line, or more commonly over two separate 12V lines. Compare my FSP ATX-350PNR with its older brother - 20A on 3.3V, 16A on 5V and two 12V lines delivering max 23A together.

Then PCIe came along and also moved most of the heavy lifting to 12V. So the two biggest draws were now both on 12V, and 5V basically just serviced the legacy PCI bus and some I/O. A recent 350W PSU (say for comparison's sake the FSP350-60APN) delivers 21A on 3.3V, 15A on 5V and max 32A on two 12V lines (note again that these currents don't add up to 350W, because no PSU can handle the max current on all lines simultaneously).

Now, the problem is one of efficency. A PSU is most efficient at about 80% load. If you only load the 5V line on a modern PSU, even if you completely max it out, the total load will be far below that 80%. That's bad for your electricity bill, but as energy is never lost, only converted, that "lost" energy is converted to heat, and heat is evil, because it stresses compontents (those poor caps that have a tendency to die anyway) and causes noise when you try to get rid of it.

TLDR: it's about balance. An early ATX PSU is well-balanced for a So7-SoA system, but unsuited to anything newer. A recent ATX PSU is well-balanced for an ATX12V+PCIe system, but unsuited to much older systems.

But that said, you only really hit problems on later So370 and particularly SoA systems with CPUs (and GPUs) that consume many times the stuff you intend to use here.

tanasen wrote:

[...]

How much power do I need over the 5V rail for such build? My little seasonic has 14A output on the +5V rail. Is this enough? Also, about the adapter, do I need one with a power switch and -5V conversion?

-5V is only relevant for a few old ISA cards. It's unlikely that ESS1868F needs it.

As for how much you need, if you assume that the CPU and PCI cards draw all their needs from 5V and round up decimals, you get 16W for the CPU, 4W for the Riva and 3W for the Voodoo1. That gives you 23W. As W=V*A, that means less than 5A on the 5V line. So 14A will do the trick esaily. But you'd be better off with a lower-rated (but still good quality) PSU, say a 1990's ATX (or even better: AT) 200W PSU. That would probably still offer you more on the 5V line than 14A, but with far less unused capacity on the 12V (all the more so as you're not using a real HDD), so it would be a lot more efficient = cooler. However your modern Seasonic won't spontaneously combust if you use that for now - just be aware that a period PSU - even one with a much lower rating - would be a better idea if you see one.

Reply 9 of 22, by Ozzuneoj

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Is an old inefficient PSU from the 90s (with all original parts) really better than a modern one when the requirements are so low? Newer units are so much quieter too.

Now for some blitting from the back buffer.

Reply 10 of 22, by gdjacobs

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Newer power supplies don't feature a -5V rail. This may not be a big difference depending on the peripherals you use.

All hail the Great Capacitor Brand Finder

Reply 11 of 22, by tanasen

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dionb wrote:

Solution is quite simple really - if you have a Voltage meter. "+5V" is exactly what it sounds like. So if you check the pins one by one measuring between the pin and a known ground, you should find the two +5V pins easily enough. If they're at the same end of the block, you have the new pinout and can just plug in a regular 2x USB bracket. If they're at opposite ends of the block you have the old one and need to somehow turn around half the connector (exactly what options you have depend on the connector itself)

My dad has several Voltage meters so it shouldn't be a problem to check out the USB pins. That is once I get a power adapter or an AT psu.

dionb wrote:

As for how much you need, if you assume that the CPU and PCI cards draw all their needs from 5V and round up decimals, you get 16W for the CPU, 4W for the Riva and 3W for the Voodoo1. That gives you 23W. As W=V*A, that means less than 5A on the 5V line. So 14A will do the trick esaily. But you'd be better off with a lower-rated (but still good quality) PSU, say a 1990's ATX (or even better: AT) 200W PSU. That would probably still offer you more on the 5V line than 14A, but with far less unused capacity on the 12V (all the more so as you're not using a real HDD), so it would be a lot more efficient = cooler. However your modern Seasonic won't spontaneously combust if you use that for now - just be aware that a period PSU - even one with a much lower rating - would be a better idea if you see one.

I found from a local ad a DTK PTP-2008.Is that an AT or an ATX psu? It is rated at 20A on the 5V rail.

PC1😜 III-S 1.4GHz, GA-6VTXE, 512MB SDRAM, Albatron FX5900XTV 128MB, SB Live! 5.1
PC2😜 III 800MHz, MS-6178, 256MB SDRAM, 3DFX Voodoo3 2000 PCI, Creative CT4810
PC3😜 MMX 200MHz, SY-5EAS5, 128MB SDRAM, Diamond Monster 3D, Diamond Viper V330, ESS 1868F

Reply 12 of 22, by KCompRoom2000

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dionb wrote:

don't expect much from USB1.0 and Win95OSR3. HID (keyb/mouse) might work, but that's about it. If you want any more, use at least Win98SE - and even there expect fun to get drivers for things like storage working.

Forget about the rumors on how limited USB support is on Windows 95 OSR2.x, functional USB mass storage drivers do exist for OSR2.1 and 2.5, you just need to know where to look.

Here are a few solutions that I'm aware of:
- XUSBSUPP - Recommended for "new" installations without the USB Supplements already installed.
- RLUSB (available at rloew's website - Click on "SOFTWARE CATALOG", scroll all the way down, then click on "FREE SOFTWARE" to find it.) - For Windows 95 OSR2.1/2.5 installations with the USB Supplements pre-installed.
- Another USB Mass Storage driver intended for Cruzer flash drives, but should work on other brands.

Hopefully anyone on here finds this useful.

Reply 13 of 22, by dionb

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Ozzuneoj wrote:

Is an old inefficient PSU from the 90s (with all original parts) really better than a modern one when the requirements are so low?

It depends how extreme it all is.

Take this graph from a 2016 PSU buying guide at Tom's Hardware:
aHR0cDovL21lZGlhLmJlc3RvZm1pY3JvLmNvbS8yLzcvNTgzMjc5L29yaWdpbmFsL2NoYXJ0LmpwZw==
This is the overall efficiency of a PSU at a given load. Let's say the new PSU we are talking about compares to the upper curve (which is likely) and the old, good quality PSU, is the lower curve. At the same overall load with the same rated power, the new one beats the old one hands down at every level.

But...

Let's say you need 15A on the 5V line. You'd need at least a 350W new PSU to deliver that, but you could get the same out of a 175W old PSU. That means the bottom line shifts to the left. There comes a point where the two lines meet. Also note that this graph assumes overall load to be similar on the lines. Particularly the 12V2 line not used for spinning drives is almost completely unloaded on an old non-ATX12V system, and that imbalance leads to more inefficiency than this graph shows.

With extremely low power draw such as a single Pentium MMX, it's probably not going to matter, but with an AthlonXP and a big AGP card it's entirely likely that the old PSU will be significantly more efficient.

Talking about efficiency and minimizing noise and heat, the best (albeit by no means the most authentic) solution for specifially this system is to go for a PicoPSU 120W, which is completely passive and takes an external 12V input and gives you 20p ATX and 6W on the 5V line, plus a Molex and a mini-Molex. If you want the option to go for beefier cards, the PicoPSU 200W might be a better match.

Newer units are so much quieter too.

sually very true. One thing I (almost) always do is replace the fan in old power supplies. I have some beautiful temperature-controlled Arctic Cooling 80mm ones I use for that purpose when possible.

tanasen wrote:

[...]

I found from a local ad a DTK PTP-2008.Is that an AT or an ATX psu? It is rated at 20A on the 5V rail.

I see conflicting reports on whether it's AT or ATX. Either way 20A on 5V at 200W is exactly the sort of PSU I was referring to. I can't comment on the quailty or efficiency of DTK as it's not a brand I'm familiar with.

With AT PSU's beggars really can't be choosers and you generally need to take whatever you can get. Early ATX PSUs are rather more plentiful. I'd recommend looking for one with active PFC, both for voltage stability and efficiency. A lot of people have an Antec fetish and their PSUs command a premium, but they used awful caps which almost always need replacing 20 years on (or - far - less) and they represent bad value for money. Instead I tend to look for FSP (frequently rebranded as AOpen) and Seasonic - IMHO better quality than Antec for a much lower price. That FSP350-60PN I mentioned earlier is just about the ultimate early ATX PSU in my eyes, with buckets of power on the 5V line, active PFC and even a SATA connector thrown in for a modern drive. Only thing is that it's overpowered for So7-type stuff, so I'm looking for it's 200W sibling.

Reply 14 of 22, by tanasen

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KCompRoom2000 wrote:

Here are a few solutions that I'm aware of:
- XUSBSUPP - Recommended for "new" installations without the USB Supplements already installed.

Yes, that's the driver I was planning on using, not the NUSB33 one; I got confused there.

dionb wrote:

I see conflicting reports on whether it's AT or ATX. Either way 20A on 5V at 200W is exactly the sort of PSU I was referring to. I can't comment on the quailty or efficiency of DTK as it's not a brand I'm familiar with.

You 've been very helpful. I 've contacted the seller but no replies just yet. I'll continue my research, but I believe I'd be better off with a more modern ATX psu with a power adapter.

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Reply 15 of 22, by PCBONEZ

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dionb wrote:

I'd recommend looking for one with active PFC, both for voltage stability and efficiency.

Contrary to deliberate public misinformation (and advertising claims by inept dealers) PFC has no benefits to end users at all.
It doesn't do a thing for stability and the only thing it makes more efficient is the power meter on your house.

Since when does adding more heat dissipating parts to achieve the same output (say powering the same PC) make something more efficient?

What set the whole PFC craze off was EU power companies pushing legislation through because with PFC their meters read a smidgen higher than without it.
Everything else about PFC is just a smoke screen. It doesn't help YOU at all.
Unfortunately politicians globally are that stupid so now it's every where.
.

GRUMPY OLD FART - On Hiatus, sort'a
Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.

Reply 16 of 22, by Ozzuneoj

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dionb wrote:
It depends how extreme it all is. […]
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Ozzuneoj wrote:

Is an old inefficient PSU from the 90s (with all original parts) really better than a modern one when the requirements are so low?

It depends how extreme it all is.

Take this graph from a 2016 PSU buying guide at Tom's Hardware:
aHR0cDovL21lZGlhLmJlc3RvZm1pY3JvLmNvbS8yLzcvNTgzMjc5L29yaWdpbmFsL2NoYXJ0LmpwZw==
This is the overall efficiency of a PSU at a given load. Let's say the new PSU we are talking about compares to the upper curve (which is likely) and the old, good quality PSU, is the lower curve. At the same overall load with the same rated power, the new one beats the old one hands down at every level.

But...

Let's say you need 15A on the 5V line. You'd need at least a 350W new PSU to deliver that, but you could get the same out of a 175W old PSU. That means the bottom line shifts to the left. There comes a point where the two lines meet. Also note that this graph assumes overall load to be similar on the lines. Particularly the 12V2 line not used for spinning drives is almost completely unloaded on an old non-ATX12V system, and that imbalance leads to more inefficiency than this graph shows.

With extremely low power draw such as a single Pentium MMX, it's probably not going to matter, but with an AthlonXP and a big AGP card it's entirely likely that the old PSU will be significantly more efficient.

Talking about efficiency and minimizing noise and heat, the best (albeit by no means the most authentic) solution for specifially this system is to go for a PicoPSU 120W, which is completely passive and takes an external 12V input and gives you 20p ATX and 6W on the 5V line, plus a Molex and a mini-Molex. If you want the option to go for beefier cards, the PicoPSU 200W might be a better match.

Newer units are so much quieter too.

sually very true. One thing I (almost) always do is replace the fan in old power supplies. I have some beautiful temperature-controlled Arctic Cooling 80mm ones I use for that purpose when possible.

tanasen wrote:

[...]

I found from a local ad a DTK PTP-2008.Is that an AT or an ATX psu? It is rated at 20A on the 5V rail.

I see conflicting reports on whether it's AT or ATX. Either way 20A on 5V at 200W is exactly the sort of PSU I was referring to. I can't comment on the quailty or efficiency of DTK as it's not a brand I'm familiar with.

With AT PSU's beggars really can't be choosers and you generally need to take whatever you can get. Early ATX PSUs are rather more plentiful. I'd recommend looking for one with active PFC, both for voltage stability and efficiency. A lot of people have an Antec fetish and their PSUs command a premium, but they used awful caps which almost always need replacing 20 years on (or - far - less) and they represent bad value for money. Instead I tend to look for FSP (frequently rebranded as AOpen) and Seasonic - IMHO better quality than Antec for a much lower price. That FSP350-60PN I mentioned earlier is just about the ultimate early ATX PSU in my eyes, with buckets of power on the 5V line, active PFC and even a SATA connector thrown in for a modern drive. Only thing is that it's overpowered for So7-type stuff, so I'm looking for it's 200W sibling.

I don't know, I'm not really seeing any actual evidence that there are tangible benefits to using old power supplies over new ones with adapters. A modern PSU running at an extremely low load isn't going to create more heat than if the PSU were run at a much higher load as it was i intended to. 50% efficiency at 30w is still only pulling 45w. Running the same unit in a modern system with an 80-150w load is always going to produce more heat, and any good unit is certainly capable of handling this.

I'm certainly not a capacitor alarmist (I use old power supplies all the time) but when very high quality refurbished or "new pull" Seaaonic units can often be found for less than $10 online, and ATX to AT (with -5v) adapters area also easy to find, I don't see how it'd ever be more practical or safer to seek out a hard to find 25+ year old PSU. I have a bunch laying around and I basically stopped using them because of the noise. I keep them just in case I ever find a scenario where they show some benefit but I have yet to have this happen. I bought about 20 Seasonic 350 and 550 watt 80plus (white and bronze) units in bulk on eBay a couple years ago for about $150 total, and I bought several ATX to AT-5v and ATX -5v adapters at a good volume discount (around $7 each I think). As long as the caps hold out, I should be good on power supplies for quite some time.

The exception to all of this would be if the system is being built with period correct hardware in mind... Then sure, use an authentic AT supply. But if you can't find a good one for a decent price with some guarantee that it works, just use an ATX.

Now for some blitting from the back buffer.

Reply 17 of 22, by PCBONEZ

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=== TDP
I know most everyone uses TDP to determine power use by the CPU (I did too) but that is not very accurate.
The watts used for TDP are not watts of power consumption, they are watts of heat dissipation.(heat losses.)
If you read Intel docs TDP is Intel's estimate of the minimum cooling needed to keep internal temps below limits under all operating conditions expected in normal use. (None of that tells you power consumption.)
IOW TDP relates to how big a cooler you need, not how big a PSU.
I think adding 10% to the TDP is prudent, but that's just me.

=== VR
Everyone seems to forget that there is a voltage regulator between the CPU and the PSU.
Those are not particularly efficient and you need to adjust for the power loss.
I guesstimate that any such VR made before the DDR RAM era is no more than 65% efficient.
So you need to multiply the TDP by 1.54 to correct for VR efficiency loss.
Thus with VR efficiency losses a 20w CPU will put 30.8w of load on the PSU.

=== 1998 Intel ATX PSU Design Guide.
It's in the next link....
=> In it you can see the recommended power distributions (configurations) for late 1990's PSUs.
That is the time period when some motherboards had both AT and ATX power.
Early on the power requirements for AT vs ATX mobos were virtually identical.
Initially all that happened with ATX was some 5v loads (mobo chips) were changed to 3.3v power.
(Obviously the so called "P4 Plug" did not show up before P4. Early ATX mobo/PSU did not have it.)

Look in section 3.3 - Starts at page 12 - Tables 4 through 7
https://paginas.fe.up.pt/~asousa/pc-info/atxp … _pow_supply.pdf
On the right side there is a total combined watts for 3.3v + 5v.
You can calculate/convert from ATX to AT mobo needs by assuming the combined watts total is all on 5 volts.
[ Divide the watts by 5 to to get amps at 5v. ]
At that time CPUs were still on the 5v rail so no conversions for 12v are needed.

======================
Summarizing some of what is in Intel's PDF in case the link goes dead.
A 160w PSU needs 110w available (on 3.3v+5v) which is 22a if 5v only.
A 200w PSU needs 125w available (on 3.3v+5v) which is 25a if 5v only.
A 250w PSU needs 145w available (on 3.3v+5v) which is 29a if 5v only.
A 300w PSU needs 220w available (on 3.3v+5v) which is 44a if 5v only.

Lovers of the ATX to AT adapters would be well advised to choose PSUs that can provide that many 5v amps.
Many (maybe most by now) newer consumer PSUs can't do it. Not even enough 5v to replace an old 160w AT.
I don't care if it's a 1000w PSU. If it has less than 110w on 3.3+5v it's under rated.
.

Last edited by PCBONEZ on 2018-04-22, 09:09. Edited 2 times in total.

GRUMPY OLD FART - On Hiatus, sort'a
Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.

Reply 18 of 22, by Ozzuneoj

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PCBONEZ wrote:
=== TDP I know most everyone uses TDP to determine power use by the CPU (I did too) but that is not very accurate. The watts use […]
Show full quote

=== TDP
I know most everyone uses TDP to determine power use by the CPU (I did too) but that is not very accurate.
The watts used for TDP are not watts of power consumption, they are watts of heat dissipation.(heat losses.)
If you read Intel docs TDP is Intel's estimate of the minimum cooling needed to keep internal temps below limits under all operating conditions expected in normal use. (None of that tells you power consumption.)
IOW TDP relates to how big a cooler you need, not how big a PSU.
I think adding 10% to the TDP is prudent, but that's just me.

=== VR
Everyone seems to forget that there is a voltage regulator between the CPU and the PSU.
Those are not particularly efficient and you need to adjust for the power loss.
I guesstimate that any such VR made before the DDR RAM era is no more than 65% efficient.
So you need to multiply the TDP by 1.54 to correct for VR efficiency loss.
Thus with VR efficiency losses a 20w CPU will put 30.8w of load on the PSU.

=== 1998 Intel ATX PSU Design Guide.
It's in the next link....
=> In it you can see the recommended power distributions (configurations) for late 1990's PSUs.
That is the time period when some motherboards had both AT and ATX power.
Early on the power requirements for AT vs ATX mobos were virtually identical.
Initially all that happened with ATX was some 5v loads (mobo chips) were changed to 3.3v power.
(Obviously the so called "P4 Plug" did not show up before P4. Early ATX mobo/PSU did not have it.)

Look in section 3.3 - Starts at page 12 - Tables 4 through 7
https://paginas.fe.up.pt/~asousa/pc-info/atxp … _pow_supply.pdf
On the right side there is a total combined watts for 3.3v + 5v.
You can calculate/convert from ATX to AT mobo needs by assuming the combined watts total is all on 5 volts.
[ Divide the watts by 5 to to get amps at 5v. ]
At that time CPUs were still on the 5v rail so no conversions for 12v are needed.

======================
Summarizing some of what is in Intel's PDF in case the link goes dead.
A 160w PSU needs 110w available (on 3.3v+5v) which is 22a if 5v only.
A 200w PSU needs 125w available (on 3.3v+5v) which is 25a if 5v only.
A 250w PSU needs 145w available (on 3.3v+5v) which is 29a if 5v only.
A 300w PSU needs 220w available (on 3.3v+5v) which is 44a if 5v only.

Lovers of the ATX to AT adapters would be well advised to choose PSUs that can provide that many 5v amps.
Many (maybe most by now) newer consumer PSUs can't do it. Not even enough 5v to replace an old 160w AT.
I don't care if it's a 1000w PSU. If it has less than 110w on 3.3+5v it's under rated.
.

This is all good data to have.

Thankfully, the PSUs I mentioned have respectable 3.3 and 5v rails and maximum loads for them. The 350ET has 20a each on 5 and 3.3, with a maximum of 130W combined. The 550HT has 24A and 30A on 3.3 and 5v, with a max load of 170W combined.

Either of these would be more than enough for most people's retro systems (aside from maybe some Katmai or Socket A systems with lots of extra components and high wattage CPUs), and they're 80plus certified and have nearly silent cooling fans. Plus they're Seasonic and if you look them up on eBay you'll find lots of them for very low prices. Not as low as they were a couple years ago, but that's why I stocked up. 😀

Now for some blitting from the back buffer.

Reply 19 of 22, by gdjacobs

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PCBONEZ wrote:

What set the whole PFC craze off was EU power companies pushing legislation through because with PFC their meters read a smidgen higher than without it.
Everything else about PFC is just a smoke screen. It doesn't help YOU at all.
Unfortunately politicians globally are that stupid so now it's every where.

Power utilities love PFC (as well as motor soft starters and client side harmonic filters) because they're better able to fulfill their mandate without spending extra on bigger conductors, bigger transformers, or other equipment for supporting and correcting voltages. For business, it can sometimes matter because utilities usually charge commercial services on apparent power (Volts RMS * Amps RMS). Consumers are usually charged based on real power used (Volts RMS * Amps RMS * PF). Furthermore, as PCBONEZ said, extra waste energy for your house (and therefore cost) based on slightly more current flowing through your service is negligible, so your direct bill is likely not impacted. Whether PFC helps utilities control costs and hypothetically your electrical rates is another question.

The other thing to consider is that vintage computers generally aren't run as long or as often as modern systems. Priority should be with improving the efficiency or reducing power usage of devices that are used the most.

All hail the Great Capacitor Brand Finder