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Vid card "requires" 400W+ PSU?

Last response: in Components
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June 11, 2012 5:47:45 AM

Ok, I'm looking for an explaination here.

I have a Gateway PC with an i3 2120 processor and a 300W LiteOn PS-6301-08a psu that came with it, and an integrated video card.

I also have an HD 5570 video card (1GB, DDR3) (the sapphire version).

Here's my question: the sapphire and amd websites both say that the 5570 "requires 400W+ psu". However, in nearly every thread I've come across on this subject

http://www.tomshardware.com/forum/339263-33-best-graphi...

http://www.tomshardware.com/forum/331101-33-best-video-...

People suggest the HD 5670, which has very similar specs (and the same "400W+ requirement" on the amd website).

Can someone explain the discrepancy? Will I be okay using my 5570 with my system without upgrading the PSU?

Thanks!

More about : vid card requires 400w psu

a b U Graphics card
June 11, 2012 6:01:42 AM

You shouldn't need to upgrade the PSU with that card, but it would be nice to know what the amps on the 12v rail is before I can say for sure. The card should not ever pull 70w from the PSU, but the amps are a different story. 16amps on the 12v rail for ex and the 5570 might work for awhile, but you may end up frying the PSU and/or other hardware along with it.

Edit: I did end up looking you PSU up, total combined amps on the 12v rail is around 23amps (10a 12v1 - 13 12v2). So in other words you should be fine.
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a b ) Power supply
a c 142 U Graphics card
June 11, 2012 6:02:15 AM

The GPU manufacturers like to overstate the power requirements of their cards when recommending a PSU. This is because there are a lot of really bad quality power supplies out there that can't deliver the wattage they promise. So to err on the safe side, they recommend a much stronger PSU than actually needed, so they don't have lots of angry customers yelling at them because their power supply can't provide enough juice to power the video card.

The 5570 uses very little power in actuality, something around 40 Watts maximum. An i3 2120 system without a graphics card will probably pull 200 watts at most. So you do have some headroom to add a graphics card, though you don't want to get a card that needs a 6 pin auxiliary connector (card that needs more than 75 Watts), that would likely take you over 300 Watts.

The very best card that you can safely run on your power supply would actually be the Radeon HD 7750 (though be sure it's the one clocked at 800MHz, the 900MHz version needs more power)
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a c 111 ) Power supply
a c 109 U Graphics card
June 11, 2012 6:47:52 AM

Supernova1138 said:
The GPU manufacturers like to overstate the power requirements of their cards when recommending a PSU. This is because there are a lot of really bad quality power supplies out there that can't deliver the wattage they promise. So to err on the safe side, they recommend a much stronger PSU than actually needed, so they don't have lots of angry customers yelling at them because their power supply can't provide enough juice to power the video card.

My answer, stolen! :cry: 
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June 11, 2012 2:14:07 PM

Thanks a lot guys, I appreciate it! What you guys are saying makes sense, and I am happy to confirm that I don't need to upgrade my PSU just to play Starcraft II and Diablo III on medium-low settings :-)
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a b ) Power supply
a b U Graphics card
June 11, 2012 3:49:26 PM

The answer is because a cheap generic psu of 750w may only actually put out 450w.

That's why you don't buy crappy generic psu's.

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