I need a PSU with a strong 5V rail! Or do I?

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gyuuula

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May 7, 2017
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Hi peeps!
I recently upgraded my old socket 939 "retro-gaming" 😀 system (+RAM, better CPU, better GPU), and my old PSU will not cut it.. My problem is that new PSUs have a relatively weak 5V rail. According to outervision dot com, I will need at least a 19A 5V rail, and 3.3V+5V combined 125W capable PSU.

I don't want to spend too much on it, in the 50-70$ range I found that the Akyga AK-P4-600 PSU would be perfect candidate. It is a mid-range product from Akyga, I haven't found anything on this specific model, but their low-end stuffs are fairy notorious fire-hazard, but their "high"-end PSUs seem to be at least decent.

Other brands I have found are Chieftec (19A, 130W) and FSP (24A, 123W) PSUs, but according to their datasheet, their 5V rail barely cut the minimum requirements.

Which PSU should I get? Akyga? Will the Chieftec/FSP's 5V rail suffice? Or should I search for a used PSU with a strong 5V rail?
 
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If the motherboard is new enough to have an ATX12V connector for the CPU, then the load on 3.3/5V shouldn't be that high. Modern PSUs have 'weak' 3.3/5V rails because ever since ATX12V/EPS12 (~2002), all major loads have been shifted to the 12V rail(s).

What actual hardware is in there including the PSU? Your old PSU could be failing to power the PC simply because its output capacitors are worn out.
 
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Hmmm, i think you shouldn't put any pass in outervision.com!! :)

Any decent midrange PSU will do fine. And you won't have any problems with the 5V rails. List your specs, so we can better determine wattage.

Any of following are sufficient for a decent high end desktop with most modern CPU's, 16gb ram, HD/SSD/and any top end GPU.

EVGA G2/G3 650w, Corsair CX650m, Seasonic S12II 620. They are all good PSU's with decent warranties, and won't break the bank.

I don't mean to be disrespectful, but that Akyga PSU, well, there are no reviews available for it (non that are reputable) for which there is most likely a very good reason. It's a piece of junk. If you have built a new system, i would not be putting that PSU in there with my fancy new components.
Don't make the mistake of getting a cheaper model like that. It has 70 percent efficiency, isn't even 80plus rated (in any meaningful way - which means it's probably not even putting out anywhere close to 600w) The PSU is as important as any component, but having a decent one will save you some headaches, and more money down the line.

If you have a budget, a place you can purchase from, then fill us in and we can help you choose something more appropriate.

You are focusing on the wrong variables with regard to PSU purchase. 5v rails are relevant, but it's the 12v rail that is more important.

edit: i wouldn't touch that akyga with a barge pole : http://www.akyga.com/default/images/etykiety-znamionowe/Sticker_AK-P4-600.jpg
 
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Athlon 64 (1.8Ghz) 3000+ -> Opteron 180 (2x2.4Ghz)
6600GT -> 8800GTS
2x1Gb DDR400 + 2x1Gb DDR400
350W FSP ATX 350PNR -> ???

My old PSU is rated for 16A for the 5V rail. If I install the two 1Gb module, the system will not boot up. Those old DDR1 modules are pulling a lot of current, much more, than the modern DDR3 or DDR4 modules.

Don't judge me, but I still have my 486DX sitting in the corner. Old stuff 😀

An 500W PSU would suffice, but most new PSU has a weak 5V rail. And those old DDR1 RAMs are sucking up a lot of current from the 5V rail.
 
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Huh, no, DDR1 doesn't draw much current. Memory chips have always been around 300mW a piece and 2-3W per DIMM. As memory chips go down in operating voltage, most of the power budget gets spent on cranking up frequencies and density which increases current draw, making the overall power roughly constant. DIMMs may get warm due to poor ventilation but they have never been a major power draw in any conventional PC.

I booted my old P4 (which has 3GB of DDR1-400) just for fun, measured current by separating each rail's wires at the PSU using a clamp-meter and it is drawing 1.5A on the 3.3V rail, 7A on 5V and 5A on 12V while running Prime95 mix. The DIMMs barely warmed up, which means most of that 35W on the 5V rail was going elsewhere.
 
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Thank you very much! According to outervision, a 1 Gb RAM stick should consume 12W power... BOLLOCKS! I found it weird they barely warm up, as they must have active cooling installed on them at such power-draw. 😱
 
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I think you just have incompactible RAM. And if you go with 8800GTS, check 12v current. My 350w was heating way too much after replacing 6600GT with 8800GTS. Replaced PSU with 400W and all was well. I have 450w semi-modern Modecom psu with PGA 478 system and it stays cool and stable. Hope that will be enough when i can find proper AGP grapichs card.'

intel D865GLC
Pentium 4 3.00 Ghz SL6WK
2x512mb + 2x256mb DDR 400
ATI x1550 AGP
Windows XP Pro

Loving retro
 
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