12V1@17A & 12V2@17A > min 12V@20A for GPU?

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Wrick

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May 27, 2006
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I have a Antec True Power II 430W PSU, with an output of +3.3V@28A, +5V@36A, +12V1@17A, +12V2@17A, -12V@1A, +5VSB@2A.

I want to buy a eVGA 7900GT KO, which requires a minimum of 400W and minimum recommended power supply with +12 Volt current rating of 20 Amp Amps.

Basically I want to know if 12V1@17A & 12V2@17A > 12V@20A. I am fairly sure this is correct, but I am just hoping for some verification.
 
Short Answer

Yes.

Long Answer

Typically, you can combine the amps on the 12v rails. That Antec will provide a maxium of 17 amps on each 12v rail for a combined total of 34 amps. However, I am not familiar with that PSU, the actual total amp could be a little less like 30 amps. No need to worry though. If you do want to know exactly how many amps it has then check the sticker on the PSU and see if it specifically states the wattage on the 12v rails and divide by 12. That will give you the amps.

As an example, the Antec NeoHE 430 has 3 12v rails each can provide a maximum of 16 amps or an estimated 48 amps. But the combined 12v rails can only provide 384w or 32 amps (384w / 12v). Therefore, while it is possible for each 12v rail to provide 192w, the total can never exceed 384w. Any attempt to force the PSU to provide more than 384w on the 12v rails will burn out the PSU and possible cause damage to the rest of the PC.
 
No that isn't correct. Each rail is independant. The power connecters are split between the 2 rails. Half using one and half using the other. So they will only be supplying 17amps.
Now what i don't know is Weather or not there is a tolerance here. For all i know you may be able to use that PSU with the Vidoe card. But it might be best not to.
Click to expand...

You are wrong.

The suggested 20 amps is not just for the GPU, it is for the entire system. The EVA 7900GT KO only uses about 60w of power or 5 amps (58w / 12v).

Since nVidia doesn't know the exact components each person has in their PCs, they generally state that the PSU should be at least 400w and have at least 20 amps.
 
I was not able to find the wattage for the 12V1 or 12V2 or both combined. All I could find was 5V, 12V1, 12V2, and 3.3V max output was 410W.

I have used the eXtreme PSU calculator, and my PC should be fine with a 430W PSU. Even with a 30% surge compensation I am right around 430W.

I am just concerned about the amps. Will my system be stable?
 
You're heading for smoke. You need a new PSU.

Now, before you freak out, think about it for a minute and you will realize no single card can draw 20 amp at 12V without the cooling system of a internal combustion engine.
 
You're heading for smoke. You need a new PSU.

Now, before you freak out, think about it for a minute and you will realize no single card can draw 20 amp at 12V without the cooling system of a internal combustion engine.
Click to expand...

Unfortuantely, sarcasm doesn't translate that well in a forum.

Wrick might take your comment seriously instead of getting a laugh out of it.
 
You're heading for smoke. You need a new PSU.

Now, before you freak out, think about it for a minute and you will realize no single card can draw 20 amp at 12V without the cooling system of a internal combustion engine.
Click to expand...

Huh? If no single card can draw 20 amp at 12V why do I need a new PSU?

If what jaguarskx said is correct and the 20 amp requirment is recomended for my entire system, should I not be okay with the 31A for the two 12V rails combined?
 
It was a joke. Sorry. I thought the phrase Now, before you freak out.... would have indicated it was a joke. 20Amps at 12V is 240watts. What the man said above is true, 20amps is for the entire machine, not the card.

This confusion started years ago when nvidia said their 5900 needed XYZ wattage power supply, I think it was the 5900. What the reality was, was that an XYZ power supply ensured that there would be enough connectors to plug into the external connector on the card AND the remaining devices in the computer. Suddenly people started screaming that the card pulled 300 watts, or what ever it was. Seems the confussion remains to this day.

I wish they would just say This card pulls 65Watts, 5 amps on the 12V line. We recommend a power supply of 400 watts for your entire computer. Instead, we get the ambiguity of 400W power supply required with 20A on the 12V line. It says the same thing, but it's certainly not as clear as saying this card uses 5 amps!
 
Ha... I guess I did freak out a little huh?

I am learning all of this stuff as I go, and needing to know all of this electrical info on top of the computer info is begining to push me over the edge.

I agree posting what the card requires, along with recomended system specs is a great idea.
 
Yeah. Thanks. :roll: Pul-lease. There's a rule now? You don't really need to explain how to use a sarcasm tag either, but thanks for your brillant insight. :wink:

Have you ever thought that, perhaps, jokes are funnier if you don't explain them? I know text is hard to understand but I came right out and said afterwards to not freak out. And then, 2 other people came by to be sure it was clear...wouldn't want to confuse anyone so lets explain the joke. What is really needed is a straight-face icon :| Oh, look, there is one. Maybe I should have used that. 😛

Sorry, I guess I got a bit carried away there. Maybe I need to check the rules.
 
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