VOGONS


PSU for Socket A - Athlon XP 3000+

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Reply 20 of 35, by Tetrium

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The Serpent Rider wrote on 2021-11-20, 10:20:
Tetrium wrote:

You sure 2x Athlon XP (which can have a max power dissipation of up to nearly 80W) will run on 25A on the 5v rail?

From what I've seen, almost all, if not all dual Socket A mobos use additional connectors, which most likely 12v rail. So realistically - dual Tualatin setup is maximum what you can power from 5v rail via standard ATX plug. There're also limits to what ATX connector could take, before quite literally starting to melt.

I never saw a dual sA board for myself, so learning that many of these boards most likely power the (so to say) extra power from 12v is really good news! (for me as I only just now learned of this).
Tualatin should have a maximum TDP of around 35W or so? So 2 of these and a single AXP (with neither CPU overclocked that is) should be rather close when it comes to how much heat they will produce.
And I definitely agree with the ATX power connector having potential issues with melting under the stress of these CPUs, I've come across several of these myself unfortunately.

In my personal opinion I would still rather want use an older more period correct (but fully functional!!!!) PSU for such 5v heavy builds (as they worked fine back then as well), but logically it's simply a better idea to use a new PSU for this task if a proper one is available if only because of safety concerns.
Obviously for any 12v heavy rig, the easiest thing would be to simply use a modern PSU as older mainly 12v PSUs have much less merit.

I wonder if a list exists of dual sA board's 5v and 12v power draws. Like I said, I never saw one in the flesh so my knowledge of these boards is very limited.

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Reply 21 of 35, by candle_86

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You can also look for late gen Nforce2 or KT880 based boards, alot of them have the 12v plug, your looking for boards that came out after Athlon 64 though, so alot of them wont have the best overclocking, but they have the P4 Plug

Reply 22 of 35, by The Serpent Rider

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Can't have AGP 3.3v on those. Well, not without slot mod at least.

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Reply 23 of 35, by OMORES

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Usually cheap PSUs claim to have high amperage on 3.3 and 5V rails so numbers can add up to a 600-700W total.

Take a look at this one... 35A + 38A...

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Reply 24 of 35, by RaiderOfLostVoodoo

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The Serpent Rider wrote on 2021-11-24, 13:25:

Can't have AGP 3.3v on those. Well, not without slot mod at least.

Correct.
KT333CE is the latest for AMD which still supports a Voodoo5 5500.
KT333CF is a downclocked KT400, so it doesn't have an universal AGP slot anymore. Compare A7V333 and A7V333X.
The board which the OP has is already the best one for this purpose.

Valentyn wrote on 2020-10-17, 18:42:

Motherboard: Epox 8K5A3+

I want this board! But they're never for sale on Ebay. 🙁
Currently using a MSI KT3 Ultra2, which is one of the very few boards which has a KT333CE northbridge and VT8235 southbridge (USB 2.0). There aren't really any alternatives. Both Asus and Gigabyte never released a board with these 2 chips.

Reply 26 of 35, by imi

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there are also some Socket A boards around that have a P4 connector and use 12V for the VRM for an easy solution ^^

e: I see this has been talked about already ^^

The Serpent Rider wrote on 2021-11-24, 13:25:

Can't have AGP 3.3v on those. Well, not without slot mod at least.

I used to have a K7T Turbo2 in my Socket A machine back in the day, and afaik it supports 3,3V AGP

Reply 27 of 35, by The Serpent Rider

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I used to have a K7T Turbo2 in my Socket A machine back in the day, and afaik it supports 3,3V AGP

Which is older and use SDRAM.

You can mod some (or maybe all) nForce 2 motherboards to work with AGP 1.0 cards by directly attaching 3.3v rail to AGP port. Or by doing something ingenious like this: https://www.youtube.com/watch?v=FxTqqTnMRIg

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Reply 28 of 35, by gdjacobs

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The Serpent Rider wrote on 2020-10-17, 18:48:

You want at least 30A there for high-end AthlonXP CPUs.

That's a common myth. You don't need that much current. Modern PSU with 25A should more that enough.

The XP 3200+ Barton does require a lot of current given the maximum TDP of about 75W or 80W (depending on FSB clock). Given conversion losses on the motherboard, budgeting 20A for the CPU alone (if supplied off the 5V rail) isn't unreasonable. Depending on other peripherals drawing off the same rail and providing some margin to avoid stressing components, 30A on 5V isn't an outrageous target.

Lower performance cores, of course, require less current.

All hail the Great Capacitor Brand Finder

Reply 29 of 35, by RaiderOfLostVoodoo

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The Serpent Rider wrote on 2021-11-25, 11:09:

That one is ok too, I guess.
Other brands include Biostar, Elitegroup or QDI. Not the best ones. There's no Asus, Gigabyte, Abit or DFI with these two chips.
The Soyo Dragon has USB 2.0, but it's done with an extra chip. It has the old southbridge, which has less PCI bandwith.

imi wrote on 2021-11-25, 11:18:

I used to have a K7T Turbo2 in my Socket A machine back in the day, and afaik it supports 3,3V AGP

That's a KT133. While it would be suitable for a Voodoo5 5500, it's too weak for a GeForce FX5950.
Not everyone has space for 10-20 period accurate machines. Using a KT333 and swapping between V5500 and FX5950 makes a lot of sense in this case.

Joseph_Joestar wrote on 2020-10-17, 18:46:

I ended up getting a used LC Power branded PSU from the early 2000s for mine, and it has served me well so far *knock on wood*.

You like to live dangerous, eh?

cyclone3d wrote on 2021-11-19, 19:41:

The thing about the recommended PSU specs is that the mfgs have to put in a way higher number than is actually needed, especially back then as you would have PSUs being sold as double or more of what they could actually handle.

Put the load on them they claim to be able to do and you would end up with fire or smoke.

Yeah, always assume the customer is a complete moron.

kdr wrote on 2021-11-20, 03:14:

So I'm currently searching for a more suitable PSU for this build. I think the presence of a -5V rail is a good indicator of a supply's "vintageness". (Wonder around what year the -5V started to disappear?)

You don't need -5V for an Athlon XP build. That's a thing for builds with ISA slots.
-5V became optional with ATX 1.3 I think or maybe 1.2. An ATX 2.0 PSU isn't allowed to have -5V. So -5V vanished around 2004.

Reply 30 of 35, by Joseph_Joestar

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RaiderOfLostVoodoo wrote on 2021-11-26, 00:16:
Joseph_Joestar wrote on 2020-10-17, 18:46:

I ended up getting a used LC Power branded PSU from the early 2000s for mine, and it has served me well so far *knock on wood*.

You like to live dangerous, eh?

I'm aware that LC Power isn't the best PSU brand, and that they sometimes shall we say "overstate" their specs. However, I still use them in some of my retro systems for a couple of reasons.

First, their PSUs are among the last ones to have a functional -5V rail. And most of my builds do have ISA slots, yes even the AthlonXP one. I don't expect that I'll be using a PAS16 or something in that particular build, but you never know. That said, I am aware that there are other solutions to the -5V problem, which don't require an "ancient" PSU.

Second, I've carefully inspected the PSU internals before using them. All the capacitors are still in visually good condition (no bulging) and of course there are no leaks. The BIOS sensors also claim that all the voltages are within tolerance range i.e. 5V is at 5.01 and so on. Everest confirms that voltages also remain within spec under load e.g. while running 3DMark 2001 or the UT '99 intro flyby sequence on a loop.

Finally, their PSUs are fairly quiet, with 12 cm fans. Not any quieter than modern PSUs mind you, but quieter than most period-correct ones with -5V rails. One last thing, I generally use LC Power PSUs which are specced much higher than what my retro rigs could draw at max load. But I would never put their "550W" PSU into a system which actually needs that kind of power.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64
PC#2: Celeron 466 / Abit ZM6 / Voodoo3 / AWE64 Gold / YMF744 / SC-155
PC#3: AthlonXP 1700+ / Abit KT7A / GeForce4 / SBLive / ALS100
PC#4: Athlon64 3700+ / DFI LanParty / 9600GT / X-Fi Titanium

Reply 31 of 35, by agent_x007

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I actually bought a LC Power 550W for my ISA + Socket A/370 needs recently.
Here's how it looks (outside and inside), it's LC Power LC6550 rev. 2.03 :
psu-jpg.225543
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fan-jpg.225545
ac-jpg.225546
dc-jpg.225547
cap1-jpg.225548
cap2-jpg.225549
cap3-jpg.225550

I own a AX860 for my 12V platforms, so I don't expect to run this near it's limits.

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Reply 32 of 35, by Joseph_Joestar

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agent_x007 wrote on 2021-11-26, 11:45:

I actually bought a LC Power 550W for my ISA + Socket A/370 needs recently.

Hey, I didn't get a cat with mine! That's it, I'm going to ask for a refund now. 😁

BTW, the capacitor at the very center of your second pic looks a bit suspect. Then again, I can't tell if it's actually a capacitor from that angle.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64
PC#2: Celeron 466 / Abit ZM6 / Voodoo3 / AWE64 Gold / YMF744 / SC-155
PC#3: AthlonXP 1700+ / Abit KT7A / GeForce4 / SBLive / ALS100
PC#4: Athlon64 3700+ / DFI LanParty / 9600GT / X-Fi Titanium

Reply 33 of 35, by agent_x007

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Cat thought he could hide behind it ;D

As for middle cap : I know, and you are correct - it's a bit "dome-shaped".
It's hard to get a picture of it without full dissasembly, but I tested it on S370 and so far it worked fine. I will replace it later.

Did you also check your used PSUs as well, before plugging anything to them ?

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Reply 34 of 35, by Joseph_Joestar

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agent_x007 wrote on 2021-11-26, 12:07:

Did you also check your used PSUs as well, before plugging anything to them ?

Yup, opened it up, cleared out the dust and then took a good long look at all the components. It was sold as "working, tested" but I wanted to make sure for myself before hooking it up to something valuable.

EDIT - just a word of caution for anyone else who might be considering this. It's very important to discharge the PSU completely before opening it. Otherwise, you could get a nasty electric shock, potentially resulting in a serious injury.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64
PC#2: Celeron 466 / Abit ZM6 / Voodoo3 / AWE64 Gold / YMF744 / SC-155
PC#3: AthlonXP 1700+ / Abit KT7A / GeForce4 / SBLive / ALS100
PC#4: Athlon64 3700+ / DFI LanParty / 9600GT / X-Fi Titanium

Reply 35 of 35, by The Serpent Rider

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Joseph_Joestar wrote:

Otherwise, you could get a nasty electric shock, potentially resulting in a serious injury.

*laughs in ElectroBoom*

gdjacobs wrote:

30A on 5V isn't an outrageous target.

It isn't, but stating that you need 30A as a bare minimum for such setup is not correct.

You may want higher output on 5v rail if you use a lot of hard drives in your retro system. Especially if it's something like WD Raptor or SCSI. These doom canisters consume almost 1A from 5V rail. Overclocking could also change things a bit, but from my observation - 30A is enough for mildly overclocked XP 3000+ with high-end GPU, even if ATX connector gets unpleasantly hot.

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Open up your hate, and let it flow into me