PSU power, enough?

R.C.Anderson · 14 Jun 2011 at 14:15

Got a Corsair HX750, and currently with a flashed&OCed 6950, and an OCed 5870, both at full load, and my 2500K at full load, I pull about 550W (worked out from measuring the current into my PC at around 2.4A) from the mains (so a little under 500W used by my components, assuming a 90% efficiency, which if anything, is likely to be optimistic).

I was wondering if anyone thinks I could get away with another 5870 in my machine? I'm thinking I probably could, as it will be adding less than 1/2 the power again, so would come under the limit, and as the PSU is rated to 744W on the 12V rail, that shouldn't be a problem either.

So, from above I don't think there would be much of an issue (although the PSU will be running quite close to max), but I was wondering if there's anything I haven't thought about?

Tomcat825 · 14 Jun 2011 at 14:23

I'd imagine it would be ok as it's a good quality PSU, although as you say, you'll be running it close to the max. Personally I'd try it first, if it wasn't enough then I'd just bust a nut then fork out for a 1k or 850.

hanluc · 14 Jun 2011 at 14:29

Might cope but I would imagine your PS fan becoming noisey.

R.C.Anderson · 14 Jun 2011 at 14:55

hanluc said:
Might cope but I would imagine your PS fan becoming noisey.

yea, it would be loud, but I bet a 6950, and 2x5870 fans would be louder

tidusjar · 14 Jun 2011 at 14:58

Why dont you look for a 600W+?
I'd recommend this Corsair Builder Series CX 600W V2 80 PLUS® Certified Power Supply
You could get this if you want to spend a little more

OCZ StealthXStream 2 700W Power Supply

R.C.Anderson · 14 Jun 2011 at 15:24

tidusjar said:
Why dont you look for a 600W+?
I'd recommend this Corsair Builder Series CX 600W V2 80 PLUS® Certified Power Supply
You could get this if you want to spend a little more
OCZ StealthXStream 2 700W Power Supply

Because they're definitely too low power

I've got a 750W, and not 100% sure it'll be enough, so a 600 or 700 would only just be ok for what I have at the moment.

andy_mk3 · 14 Jun 2011 at 15:24

You can pull 900w from that PSU with 80%+ efficiency, I wouldn't worry

http://www.hardwaresecrets.com/article/Corsair-HX750W-Power-Supply-Review/775/8

Tomcat825 · 14 Jun 2011 at 15:39

There ya go, your sorted.

R.C.Anderson · 14 Jun 2011 at 15:52

Ah, thanks for that link Andy, I would be a little concerned trying pulling 900W continuously, but as I'm definitely not going to get that high

Although, actually, I'm not sure that's the same, as they seem to mention that it has 2x12V rails, but I'm pretty sure mine only has the 1 (Haven't actually checked the sticker, but that's what it says on the corsair website, and I've only had it for a few months), maybe Corsair has changed their PSUs since. Just hope they're up to the same standard

EDIT: upon re-reading, I don't think they're saying it's multi-rail, it's just their tester had 2 12V readings, but they were actually from the same rail.