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Will a GPU even work if the amps on a 12v rail are to low?

Last response: in Graphics & Displays
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June 21, 2012 12:17:14 PM

So I've already made 2 post regarding an issue I was having with my GPU not being recognized. Some people told me it was my PSU and other told me that the GPU was just dead. Currently I've been searching through the internet on different similar issues and trying to learn a little bit about amp requirements. To be honest it's still not really clear to me.

I get that a low end GPU can pretty much run on the lowest PSU known to man. But a high end GPU has to have a PSU that meets certain requirements. The minimum being a 450/500 watt with at least 30 amps on the 12v rail and a PCIe 6/6+2 pin power connector (if needed).

The thing that gets me is that there's a lot of people saying that they can run certain high end GPU's with low power PSU's. Like for me I have an ATI Radeon X1950 Pro 256mb PCIe x16 card and some people have claimed to be able to use this same card with a 250 watt PSU with like 12 amps on the 12v rail. of course I understand though that by doing that, the PSU will eventually fail leading to it's inevitable replacement and sometimes the same can go for the GPU, due to damage that may have been caused by the PSU failing.

So my big question to this is; what exactly happens when you use a high end GPU with a low power PSU (less than recommended amps on the 12v rail)?

Other questions:
Will it work properly?
Will it turn on?
Will it recognize in device manager?
Will it work without crashing?

For me; the card got power, I just couldn't get it to recognize despite all my efforts to troubleshoot. Tried just about everything expect try it in another system. What confused me a bit though was some people were saying that the PSU was the culprit due to only having 15 amps on the 12v rail. While others were saying that the PSU was good enough for the card to work and play games on and that the card was probably dead.

Which brought me to wanting ask about the amps on a PSU and if a fairly high card will even work that way. Any insight on this subject wouldn't only help me, but most likely quite a few other people still wanting to know.

For those interested here's the links to my GPU and PSU:
http://www.newegg.com/Product/Product.aspx?Item=14-195-... -GPU

http://www.newegg.com/Product/Product.aspx?Item=17-339-... -PSU
a c 130 U Graphics card
June 21, 2012 1:21:59 PM

Well first of I would like to explain that you can not take the numbers for granted and that goes for PSU's and GPU spec's.

The GPU makers will overstate the needed power for the cards as a way of putting in a safety net, this in theory makes sure people don't try to run a card on a borderline capable PSU. So in that regard it makes sense to do so.
The problems start when they get over cautious.
I personally had a PC years ago that ran a range of cards from a 9800AIW to a X1650XT the latter of which uses only about 15 watts (just over 1 AMP) less that a X1950 pro. This was a single rail PSU with 18Amps on the PSU.

The listed PSU will Run the Listed card with no worries as long as the rating on the PSU is correct.

There is a rating system for how well made a PSU is, from memory it starts at Bronze and goes up to platinum with Plus ratings in between.
The PSU you listed is not rated and so the quality, which translates to how well it supplies its stated power wont be as good as a rated one. Some PSU's plain outright lie about the available power.

It may well not supply the power it states but should still easily be up to powering the card .

Are you sure the Motherboard is compatible ?

Mactronix :) 

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a b U Graphics card
June 21, 2012 1:31:23 PM

That card should work fine on that PSU, I would just recommend not Overclocking. I have an older system with a AMD 6000+ and the ATI x1800xl all in one, and the thing in running off a 250watt with 16amps, Im under the recommended watts and amps and the thing has been running games and recording TV (DVR) for years with that PSU just fine.

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Related resources
June 21, 2012 1:41:20 PM

mactronix said:
Well first of I would like to explain that you can not take the numbers for granted and that goes for PSU's and GPU spec's.

The GPU makers will overstate the needed power for the cards as a way of putting in a safety net, this in theory makes sure people don't try to run a card on a borderline capable PSU. So in that regard it makes sense to do so.
The problems start when they get over cautious.
I personally had a PC years ago that ran a range of cards from a 9800AIW to a X1650XT the latter of which uses only about 15 watts (just over 1 AMP) less that a X1950 pro. This was a single rail PSU with 18Amps on the PSU.

The listed PSU will Run the Listed card with no worries as long as the rating on the PSU is correct.

There is a rating system for how well made a PSU is, from memory it starts at Bronze and goes up to platinum with Plus ratings in between.
The PSU you listed is not rated and so the quality, which translates to how well it supplies its stated power wont be as good as a rated one. Some PSU's plain outright lie about the available power.

It may well not supply the power it states but should still easily be up to powering the card .

Are you sure the Motherboard is compatible ?

Mactronix :) 


This my motherboard:
http://bizsupport1.austin.hp.com/bizsupport/TechSupport...

Both the card and PCIe slot on the board are 1.0 x16.

Here's the exact PC itself:
http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en...

Actually should have just said here's the PC itself. It only has 2 of the 3 gigabytes of ram in it and is running windows xp pro sp3.
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June 21, 2012 10:55:14 PM

"Are you sure the Motherboard is compatible ?"

To be honest no I'm not, I'm not really sure how to check that. Assuming you weren't talking about the PCIe itself. Like I said, it just won't recognize. I mean compatible or not wouldn't it at the very least do that?
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