I am building a new rig. Planning on keeping some old parts and buying some new. I have on order these parts:
Intel Core i7-950
CORSAIR DOMINATOR 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600
EVGA GeForce 580 GTX
I have a 750W PSU and was wondering if this will be sufficient to run this rig? Will not be OCing anything right away, but it may be a possibility for the future. All of this will be stuffed into an old case, Antec Sonota II.
750 is the "red headed stepchild" of the PSU market. A 650 watter will run any single GFX card and a 850 watter will run just about every GFX card in SLI / X-Fire. The 850's are barely more expensive than a 750 and are often cheaper because more more 850s are sold.
I'd be concerned about twin 580s on a 850 watter tho. The Corsair HX750 is $130 whereas the equivalent in quality XFX Black Edition is only $110. Other quality 850 watters include the Antec SG-850 ($250) and CP-850 ($110) the later of which requires a Antec compatible case.
And yes, I'd stay away from the Ultra.
Would suggest that you consider a 570 w/ 850 watter and then add another 570 come XMas when the games released then might start to drops fps down near 30 on the most demanding new games at hi settings.
here's the frame rates for popular games for the 570 and 580 in single and SLI configurations
Card 570 580 570 SLI 580 SLI
COD-MW 148 168 230 265
BBC2 56 67 103 108
Dirt 2 80 96 138 149
Far Cry 2 85 104 153 164
Metro 2033 27 33 54 65
Dawn of Discovery 74 86 109 112
Crysis Warhead 54 62 86 90
Total 524 616 873 953
The last 2 lines "% faster" & "% more $" means for example that the 580 is 18% faster and 46% more expensive than the card(s) to the left.
With this test anyway, the twin 570's are a better bang for the buck at 80 cents per frame than a single 580 at $1.07 and they are the only one where the % increase in cost is less than the % increase in frame rates.
750w PSU should be more than enough. w/o OC, it should only need 600w-650w power from a good brand PSU (Antec, Corsair, etc).
You may want to use Antec PSU calculator, it's such a simple and nice way to calculate the needs of power of your system. http://www.antec.outervision.com/index.jsp
What are the risks of running with this junky Ultra psu? Do I risk damaging some of the components? or will it just not work and I will have to buy a new one anyway?
It depends on the load and according to the reviews your psu can barely output 450w before ripple and noise reach dangerous levels which may result in system instability and component damage and afaik the GTX 580 needs 600w psu at least so yes you are putting your system at risk by using this PSU and you better spare your PC for something better!