Are beefier PSUs efficient?

[vromanowski]

I'm about to purchase a second gtx 260 so I can put it in an SLI config, but I'm going to have to upgrade my PSU as well.
I'm debating between the Tagan BZ 900watt and the 1100 or 1300 watt. I know the 900w will be sufficient, but sometime down the road it might not be enough. I have the money for one of the beefier units, but the only reason I'm hesitent is because I don't want to have more wattage than I need if it's going to make my PGE bill higher every month. So I guess my question is, if I go ahead with the 1100 or 1300 watt, is it going to run efficiently so that I'm only drawing the power that the 900w would with my current build? hope i stated my question clearly, i just got done with 5 hours of calc and physics homework

 

[cjl]

They are efficient, but only at higher load levels. At idle, there would be some efficiency loss. A good 900W should be more than sufficient anyways, unless your future plans are something like tri 280s with 6 hard drives.

 

[13thmonkey]

a psu will only supply and 'convert' what is needed, but there is a sweet spot for efficiency, so a 900W might be 75% efficient @600W but a 1300W might only be 70% @600W realistically this means that the 1300W draws slightly 600/0.7=857W from the socket compared to 800W, so you'll be able to run the 900W system for 20hrs for the same price as 19 hours of the other system. So its not a big deal. But 900W is a lot of juice.

 

[mike99]

Check out http://archive.atomicmpc.com.au/forums.asp?s=2&c=7&t=9354
Your proposed SLI setup uses a PEAK of 270W, if you allow 100W for CPU, you need a PSU that gives about 450W on 12V rails. A good quality 550/600W will do. What make model do you have at present? You only need 1000W for triple SLI 280s and overclocked CPU!

Mike.

 

[vromanowski]

right now i have q6600 @ 3.2ghz, 4 gigs ram, a single gtx 260 core 216, and 2 hard drives. it's running on an OCZ GameXStream 700W.

 

[theAnimal]

For 2 GTX260 you will need a good quality 600W+ PSU with enough PCI-e connectors. Corsair TX750 would be good.

 

[mike99]

What you have is fine, even with 2 graphics cards.

Mike

 

[Kari]

^^+1 what mike99 said