Evert wrote:

This is beyond stupid, but you could use a Corsair AX1200i since it can supply 30A on both the 3.3V and 5V lines for a combined […]
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This is beyond stupid, but you could use a Corsair AX1200i since it can supply 30A on both the 3.3V and 5V lines for a combined output of 180W. You'd be better off looking for a second hand unit than wasting your money like this.

I upgraded my test bench PSU to a Corsair AX1200 a couple of months ago. Im using it with a Gigabyte BX2000+ board right now. Everything works great except that the -5V rail reads as -61V 😁 in the BIOS hardware monitor so I guess its not a good PSU for using with ISA cards that needs -5V. The Gigabyte board tells me to "Check system health" every post 😜

I've got that same board and it does the same thing 😀

Another solution could perhaps be to daisy chain two PSUs.

I know some Lian-Li cases and Cooler Master cases allow you to mount two ATX PSUs.

Evert wrote:

I don't have any personal experience with nForce 2 chipsets and Windows 9x, but there are numerous accounts of the drivers being unstable on Windows 9x. Not that Windows 9x is the most reliable environment to begin with. But, yes, nForce 2 boards have ATX12V connectors.

I have a Asus A7N8X-X with nforce2 and it has no ATX12V connector.

Well, that is entirely possible, but you definitely get 4-pin connectors on later VIA KT600 and nForce 2 boards. Some examples include my Soyo SY-KT600 DragonPlus 2 and the Gigabyte GA-7N400-L. That ASUS board of yours is the exception, not the rule. But for about 90% of Socket 462 boards you definitely need a beefy 5V rail.

🤣 Two PSUs, holy moly. I think I'll just go with an Athlon 64 instead 😀

Haha, yeah, I told you the Socket 462 is a real bastard to work with.

Evert wrote:

I have reason to believe that they are based on the FSP-built units that AOpen used back in the day.

I will open up an Aopen that i have and try to post some pics. I was planning on refurbing it anyway.

I actually have one too. They used very good capacitors in those units. Mine has Panasonic and Nichicons in it. I suspect StarTech will cheap out and use CapXon or Teapo capacitors.

squareguy wrote:

Does anyone have any information on the build quality of StarTech power supplies?

I did a bit of digging and it seems like StarTech's power supplies are actually built by ATNG.

Honestly, man, I'm running an Athlon 800 with an MSI KT133 board on an Allied 300W with 15A on the 5V and it does great.

That includes

Audigy Platnium, Geforce 3 Ti 500, 512mb PC133, DVD-Rom, CD-RW, 3 1/2 Floppy, Audigy Drive, Gigabit Nic, USB 2.0 4 port card, Mouse, Keyboard, Sidewinder Precision 2 Joystick, and Powered USB speakers. It does fine.

Well, sure, it'll work, but it's pretty much on the limits of its specifications. I always prefer to have some overhead, in case shit happens.

I wonder if it's possible to modify a mainboard to power the VRMs with 12V instead. Might be as easy as lifting the mosfets from the board and wiring them straight up to 12V..?

Evert wrote:

This is beyond stupid, but you could use a Corsair AX1200i since it can supply 30A on both the 3.3V and 5V lines for a combined output of 180W. You'd be better off looking for a second hand unit than wasting your money like this.

[100A at 12V]

Nice arc welder you got there. 🤣

jwt27 wrote:

I wonder if it's possible to modify a mainboard to power the VRMs with 12V instead. Might be as easy as lifting the mosfets from the board and wiring them straight up to 12V..?

Well, I'm sure there are people on the forum who are keen to try it out. It's silly, but I'd also like to see someone try a dual power supply approach. I wonder if you could connect the +5V wires from the two 24-pin ATX connectors to a single 20-pin ATX connector. Obviously you'll connect the green and black wires as well, so that both switch on at the same time. Voltage spikes could be a problem though. Not quite sure how you'll deal with it.

TELVM wrote:

Problem with group-regulated modern PSUs is not only that the +5V rectifier is relatively undersized, but also that the whole PSU is designed for the heavier +12V loads and lighter +5V loads of modern systems.

Higher quality (and more expensive) modern PSUs like the Seasonic S12G 450W (SSR-450RT), with DC-DC conversion and semi-synchronous rectification for the minor rails (as opposed to group-regulation) can handle the light +12V load / heavy +5V load scenario much better, without voltage sag in the 'Crossload 1' test:

But the +5V rail is still relatively weak at 20A tops.

I am currently in the middle of my ‘replace old PSU’s of all retro pc’s’ project. I have installed a couple new Seasonic S12II-520 and M12II-520 Evo PSU’s in my PII/PIII systems. These PSU’s seem to be perfect for an old pc at first glance: 24A on +5V, pretty good components inside, Molex plug cables included and affordable. Unfortunately after some testing I have discovered that they are no good at all. Some computers freeze running 3D Mark, some have issues in frame rate (e.g. Turok Dinosaur Hunter) and random blue screens in Windows 2000. These issues were not present with the old (and potentially dangerous) AOpen and FSP PSU’s. It seems that indeed the cross load (high load on +5V and low load on +12V) is a problem for these ‘modern’ group regulated PSU’s.

Last week I have shortly tested a Seasonic Focus Plus Gold PSU (with DC-DC conversion for +5V) and so far it tested good. I still need to test it in a benchmark though. Unfortunately it’s only designed for max. 20A on +5V with a total of 100W combined on +5V and +3.3V, so it’s not good enough for an early Athlon setup. I consider testing a be quiet! Straight Power 11 which can deliver 24A on +5V and ticks other boxes as well (in theory). Seasonic also has a high end offer, called the Prime Ultra Platinum in a 550W variant, which has an interesting micro tolerance load regulation of which I wonder how that works out in a +5V heavy sucker system. All of these PSU’s retail for ca. € 100, which is probably what it would cost to get an old PSU recapped with quality caps at a professional.

I have installed a new be quiet! Straight Power 11 450W in my Voodoo2 system. It performs well, voltages stay within 5% tolerance and this setup passed all tests in 3D Mark 99. Still, in Turok Dinosaur Hunter I initially experienced the same 0.5 second or so frame glitch / freeze. It turns out that it is caused by the optical drive speed, that initially spins the CD at various speeds and after some time slows down to what seems to be a fixed speed: frame glitch gone.

I wonder; are there any patches available for Turok Dinosaur Hunter (Glide)? I would love to play it without the CD-ROM.

So a psu with 26a will be enough Duron 850 (spitfire) and a v3 2000pci?

Why not modify a PSU to convert some of the 12v to 5v as it leaves the psu

That's a significant modification and not necessarily straightforward to complete.

how few amps can you gat away with on a 386/486 system usually without drives?