Originally Posted by danman4734
if you're going to buy a psu sure a 750w - 850w will work for you now but if you're going to upgrade hardware in the future ( custom water cooling,d5 pumps, tri crossfire 7950,ect......) don't you want something that can handle any upgrades you decide on in the future without having to buy another psu? just my 2 cents
Knowing how much power a build like that would require is a huge help. ;)
Three 7950s under full load in their system would make their PSU pull 576W from the wall outlet. Assuming the 4770K overclocked to 5 GHz will consume 150W like the 3770K, adding that to the 576W figure results in the PSU pulling 726W from the wall outlet. Adding another 50W just for good measure (to make sure to cover all possible extra goodies like a high-end water cooling system) brings that to 776W. Therefore, if the PSU is 90% efficient while pulling 776W from the wall outlet, then the computer is pulling 698W from the PSU. However, this is an unrealistic power draw because I'm saying that absolutely everything in the computer is under full, peak load. A more realistic power draw is the peak gaming power draw, and that would be closer to about 600-675W. A good quality-made 750W PSU can easily deliver 750W 24/7 if it's ever needed, and so therefore a PSU like that would be a perfect fit. It would be right in the sweet spot for maximum average efficiency.
Regarding future upgrades: each new generation of computer parts such as CPUs and GPUs especially require less power than the previous.