I just bought a second Evga GTX 480 to run SLI. I currently am using a SeaSonic X750 to power my system. Spec are:
Intel Core i5 2500K
Asus P8z68 V- Pro
Corsair Vengeance 4X4gbs @1600 DDR3
Corsair Hydro H100 cpu cooler
SeaSonic X750 watt psu
Samsung Spinpoint 1tb HDD
Liteon DVD burner with Lightscribe
TP-Link USB 2.0 wirelees adapter
Logitech G-15 Keyboard ( I just bought a Filco Ninja Majestouch-2)
Logitech G500 Gaming mouse
That's everything powered off the motherboard. Everything else has it's own power supply.
The Seasonic is a little over priced for the 1000 kw range but how many Platinum rated psu's are there out there with SeaSonic's build quality? I can get the Antec relatively cheap off ebay probably but the inline capacitors might cause problems with cable management. The Corsair should be a no brainer but it's the most expensive of the 3. Finally, both the SeaSonic and the Corsair are fully modular. I really need some input and any help would be greatly appreciated.
I don't plan on OC'ing the 2 cards but maybe the CPU. if I can get by with my current PSU I'd be ecstatic. That's money spent elsewhere, maybe on a good 120gb SSD.
How much of an overclock do plan on doing to the CPU?
At the i5-2500K's stock reference clock of 3.3 GHz the CPU VRM circuit will be drawing 75 Watts (6.25 Amps from the +12V rail(s)) at 100% CPU load.
At 4.3 GHz the CPU VRM circuit will be drawing 99.7 Watts (8.3 Amps from the +12V rail(s)) at 100% CPU load.
At 4.7 GHz the CPU VRM circuit will be drawing 134.9 Watts (11.2 Amps from the +12V rail(s)) at 100% CPU load.
For a reference clocked system running two reference clocked GeForce GTX 480 graphics cards in 2-way SLI mode NVIDIA specifies that the power supply should have a minimum combined +12 Volt continuous current rating of 63 Amps or greater and have at least two 6-pin and two 8-pin PCI-E Supplementary Power Connectors.
Your Seasonic X-Series 750W (X-750) has a combined +12 Volt continuous current rating of 62 Amps. There really isn't any spare capacity to handle any overclocking.