GTX 275 PSU question.

klizzey

Distinguished
May 19, 2008
16
0
18,510
Hello, i'm planning on upgrading my 8800 GT to a GTX 275 and had a quick question about my PSU.

I currently have the following http://www.apevia.com/ProductsInfo.asp?KEY=ATX-LCD750W which is 750W.

which uses two 12v rails at 30 amps each. I was wondering if this was enough to power the 40 amp requirement for the 275 since it required 2 6-pin connectors. The sites i've checked out have it at 730 Wattz 3.3,5,12V combined and 330W at 3.3/5V combined. Thus 330 - 730 would leave me with 400 wattz on the 12V rails. 400/12 would give me 33 amps and I don't think that's enough for the supposed 40 amp requirement on the 275. But like said, i'm not sure as to how using dual 6-pin connectors would effect that. Do the 2 30 A 12V rails provide more then 40 amp total? Would really like to step it up to the 275, but yah, would suck to purchase it and then have it not start up.
 
Solution
Looks like to me that 30A per +12V rail is the absolute max. It also says +12V, +5V & +3.3V Combined = 730W. 730-330 calculation would be correct if you assume that all your +5V & 3.3V are at max consumption of 330W. But I doubt it's the case. If it is less than 330W, therefore +12V rail wattage alone will be 330<W<730. In that case you would have more than 33Amps available to you. I would look and see what you have in there that consumes lower voltages in order to figure out how much you have left over. Generally speaking, 750W is enough for 1 GTX 275.

barmaley

Distinguished
Aug 3, 2009
95
0
18,640
Looks like to me that 30A per +12V rail is the absolute max. It also says +12V, +5V & +3.3V Combined = 730W. 730-330 calculation would be correct if you assume that all your +5V & 3.3V are at max consumption of 330W. But I doubt it's the case. If it is less than 330W, therefore +12V rail wattage alone will be 330<W<730. In that case you would have more than 33Amps available to you. I would look and see what you have in there that consumes lower voltages in order to figure out how much you have left over. Generally speaking, 750W is enough for 1 GTX 275.
 
Solution

klizzey

Distinguished
May 19, 2008
16
0
18,510
Yah, exactly what my issue here was. I looked at the watt requirement and it in no way could use just 40 amps to the card. Yet, I kept seeing all the people claiming "lala it uses 40 amps, can't get it to run" so I was kind of worried about how true that was. Just wanted someone knowledgeable's opinion.

Thanks a bunch guys! :love: