ATX Power Supply Quality

[squareguy]

The scariest part of any computer, to me, is the power supply. This one component has the potential to render every other part in the computer useless. All of those vintage, refurbished, NOS components that were painstakingly acquired over the years gone in an instant if the power supply fails in a catastrophic manner. Thankfully a good quality power supply usually does not fail in a catastrophic manner, but rather just stops functioning leaving all the other components alone. I remember the Bestec power supplies in E-Machines that were notorious for destroying motherboards when they failed.

I would venture to guess that most of us need a first generation ATX power supply, we will just refer to it as ATX 1.0. This will properly power any ATX Socket 7, Super Socket 7, Slot 1 or Socket 370 based system. It has the 20-pin ATX motherboard power connector, the proper amperage ratings on the 3.3V and 5V rails for the older CPU's and very importantly has a -5V rail for the ISA slots. New old stock ATX 1.0 power supplies are getting harder to find, especially at a good price. Many of these NOS power supplies are OEM and not retail which makes it more difficult to judge the quality based on the maker. I would love to hear from you all about which OEM power supply makers you have had good luck with or heard about from others. I would especially like to hear which makers, or models, should be avoided at all costs.

I am intently looking at this little gem and am considering buying a lot of them. http://www.ebay.com/itm/161022961204
Any thoughts on this one?

[Mau1wurf1977]

You are right, the scariest part is the PSU and it can take a lot of expensive parts with it if it fails.

Therefore I only use brand new branded ATX power supply. Mostly from XFX. Super Socket 7 is all ATX already. For AT stuff I use an adapter.

-5V is an issue if you use certain cards like the PAS16, SB 2.0 or LAPC-I. BUT an easy mod with a negative linear voltage regulator and two capacitors.

[squareguy]

For all the new stuff I build I only trust two companies. I am not saying there aren't other companies I would trust but I stick with what works for me. Seasonic and the PSU's that come with Supermicro cases like this http://www.newegg.com/Product/Product.a ... 6811152123

Ironically I am on here for games but I do not build gaming systems. I build workstations for general use mostly and 300-Watts is plenty for a Xeon with integrated graphics. They work very nicely indeed.

EDIT: I would be very interested in seeing a schematic and picture of a -5V regulator you have added to a modern ATX PSU. I may, in fact, just use a 300-Watt Seasonic PSU like this http://www.newegg.com/Product/Product.a ... 6817151086

[Mau1wurf1977]

So why don't you get such a PSU then?

Rather than these Ilssan PSP 215 Heavy Duty 200 Watt ATX Power Supply?

[Unknown_K]

The early AGP ATX systems were not that demanding for power. Even a cheap 250/300W supply that comes in NOS cheap towers work fine for those. For later generation PCIE systems (with SLI) I use cheap Cool Power supplies (last one was an CP-G880 800W supply). The 600W and 700W units work well and are cheaper.

Mostly you want a supply that if/when it does fail it doesn't take out the whole system with it. I have some other brands (purchased from Compgeeks.com when it was around) that would fail after a few years of heavy use but would not kill anything when they did. The power ratings are a bit inflated, depending witch voltage you are using most a 600W supply might only put out 450W. Get yourself a cheap PS tester and use it before connecting anything to a rare board.

[Forevermore]

Here is a very helpful link:

http://www.overclockers.com.au/wiki/Power_Supply_Unit

It also must be quite accurate as experiences reflect the information provided.

[Gamecollector]

Nay, you can use ATX 2.x PSUs with any old ATX motherboards.
The only trouble is - you need a more powerful PSU. ATX 1.x have ~50% of the power for 3.3V and 5V rails, ATX 2.x - only 20%-25%... So - 300W ATX 1.x PSU = 600W ATX 2.x PSU.
About the -5V rail - you need this rail only for some old ISA soundcards... It's not so hard to build an +5V invertor in these cases...

[TELVM]

... I may, in fact, just use a 300-Watt Seasonic PSU like this http://www.newegg.com/Product/Product.a ... 6817151086

Notable exception to the rule that cheap PSU's are junk. Teapo craps but otherwise quite decent, there is even a MOV across H-N (as rare as hen's teeth amongst unexpensive PSUs).



The 120mm fan is a blessing for cooling old cases with atrocious case ventilation, and has rpm self-regulation. Will do fine powering any low wattage relic.

... The only trouble is - you need a more powerful PSU. ATX 1.x have ~50% of the power for 3.3V and 5V rails, ATX 2.x - only 20%-25%... So - 300W ATX 1.x PSU = 600W ATX 2.x PSU ...

I think only with heavily overclocked Athlon Classic/Athlon XPs will the relatively weaker +5V rail in modern PSU's be a concern. Anything previous draws very little +5V, anything from P4/Athlon 64 draws mainly from +12V.

[squareguy]

I guess I left out an important bit of information. I know that Ilssan was one of the OEM suppliers for Gateway 2000 back in the Pentium 1 MMX days. The "Heavy Duty" bit in the eBay ad is total BS from the seller. I think it might be worth buying one, check the brand and temperature ratings on the capacitors, and most importantly look for a safety IC monitoring the outputs. 200-Watts is plenty for what I need.

I just like the original equipment when available because I know it will do what I need regardless of what card I decide to put in it.

Forevermore: Thanks for the great link.

Mau1wurf1977: I would still like to see a schematic / picture of a modded -5V rail.

TELVM: I can see a safety IC board in the output section of that PSU, what brand is it?

[GeorgeMan]

So - 300W ATX 1.x PSU = 600W ATX 2.x PSU.

Nope. A quality 700W ATX 2.x PSU can deliver only 10-20 watts more at 5v than a quality 400W. That's because nowadays +5v/+3.3v rails are not needed much and they use DC-DC converters to produce +5v from the main +12v rail.

So it IS possible to bring even a 100€+ PSU to its limits at the +5v rail, with a power hungry overclocked Athlon system.

[squareguy]

Ok, I ordered one to check it out. I will post pictures when it arrives.

[swaaye]

So it IS possible to bring even a 100€+ PSU to its limits at the +5v rail, with a power hungry overclocked Athlon system.

Fortunately lots of Athlon boards are 12v orientated.

But yeah if you just gotta have that overvolted, overclocked Palomino on a KT133A setup (or board of similar vintage) then you could possibly run into overload issues Or maybe the cheesy, low-end and now-ancient VRM hardware will just explode!

[TELVM]

... TELVM: I can see a safety IC board in the output section of that PSU, what brand is it?

No idea (pic isn't mine). Seasonic says the SS-300ET has short circuit, over voltage and over power protections.

[bristlehog]

I bought myself a Zippy HG2-6400P 400W PSU. Not that I really need 400W, just less powerful Zippy species are impossible to find in Russia.

It is reliably built, has -5v rail and got 3 years warranty. Drawbacks are:

- lack of on/off switch
- high noise level (that's a server PSU after all)
- EPS (24 Pin) to ATX (20 + 4 pin) converter cable is needed to use with ATX mainboards

[Dreamer_of_the_past]

I am thinking about buying the SeaSonic SSR-360GP since it uses Japanese capacitors. I wonder if Enermax does the same in their low wattage power supplies.

[obobskivich]

I've had good luck over the years with Antec (though I don't really like the ones with "automatic" fans that can turn on/off whenever the PSU is connected to power), Thermaltake, Corsair, and PC Power & Cooling. I've got a Thermaltake 430W in my P4 that specifies something like 35-40A on the +5V, is ATX2.x (has the P4 connector, has SATA connectors, etc) and 18A on the +12V. It's worked fine powering up Pentium MMX systems with the P4 connector just disconnected. It also has no problems powering up my Willamette, GF2 Ultra, etc system.

This model looks pretty similar to what I have, but with a 120mm fan (mine has 2x80mm - one on the bottom and one on the back), and it's still in production:
http://www.thermaltakeusa.com/products- ... C_00001967

I think 30A should be good enough for a Pentium or Athlon or what-have-you, and it's 5-10A higher than what I've seen on newer PSUs (it actually has more 5V current than either of my newer/higher-power units that drive more modern machines).

[tayyare]

300 watt old Aopen (FSP?) ATX PSUs always worked nicely for me. Still have 3 in use, without any problem. The machines that I'm powering with them are generally PIII systems. But one of them is a rather heavy build:
Two floppies - 3.5"/5.25",
DVR RW Drive
HP Dat8 backup drive
Two 512MB SDRAM sticks,
Voodoo3 AGP,
Two Voodoo2 12MB PCI in SLI,
Matrox MII with 8MB RAM upgrade
Adaptec 29160 SCSI
3com 905 NIC
SB AE64 Gold with SIMMCONN and 32MB SIMM
Three IDE Drives (30-40GB each
Five SCSI disks (36 - 73GB each)
Two very high power case fans
An AMD Athlon class CPU cooler
A USB hub
A USB CF reader
Microsoft Sidewinder joystick

[meljor]

Yep, fortron (fsp/aopen etc.) are very good psu's. You find them in many old cases and since they are mostly 250-350w they are perfect for old systems. Even if they have degraded a little over the years they have still plenty of power left for old retro systems.

I started hoarding these things recently as they cost next to nothing.

On my new and highend systems i only use Corsair and occasionally Coolermaster psu's.

[ODwilly]

I got a fsp power supply not that long ago in a p4 and was excited until I opened it up and it had a bunch of bad caps Rule #1 of old power supplies! Always open them up and check the caps.

[Evert]

I wanted to start a new topic on this, but then I realized that this is something that has been discussed before on the forum and it's best to probably contribute to what is already there. I'm in the fortunate position that I own a brand new Rosewill RV350 (ATX v1.3 spec) power supply. It has a very quiet fan and a -5V line, so it's perfect for old systems. I've recently obtained a mint condition Abit KT7A-Raid motherboard and an Athlon Thunderbird 1.4GHz CPU. This is from the era when most of the power came from the 5V and 3.3V lines, is it practically even possible to power a system like this with an ATX v2.3 power supply? You have to literally buy a 750W power supply just to get a meager 150W on both the 3.3V and 5V lines with 25A of current each. My Rosewill provides 28A for the 3.3V line and 35A for the 5V line and it can supply 200W of power to both lines. So a very powerfull modern PSU can barely meet these specifications. A Thunderbird CPU uses about 70-75W of power, an AGP slot can provide up to 50W of power to a card. RAM can use up to 5W of power, PCI cards can draw up to 20W of power. So if we add it all up that means, worst case scenario you're looking at (75 + 50 + 5 + 20)W = 150W of draw on from the 3.3/5V lines. I'm not sure what the margins are, but doesn't this mean that the PSU will more often than not shut itself down because of an overdraw of power?