Originally Posted by mifero766
I'm looking for just a nvidia 670/680 or AMD 7950/7970.
I know you can't compare the need for power on AMD/Nvidia. Also, I still don't know if i will be getting a second card or not. or do a w.cooling setup.
Just getting a huge mark allowance. I know its bad.
Anything may change depending on my time and budget
Then I'll show you the expected total maximum power draw that the system would ever pull from the PSU for both the 680 and the 7970.
First, the 680:
With one GTX 680 under full load, their power supply pulled 307W from the wall outlet. Their CPU was idling, so let's add 200W for an overclocked CPU (this is very unrealistic, so it's just for good measure). This makes the PSU pull 507W from the wall outlet if both the GTX 680 and the CPU were under maximum load simultaneously. If the PSU were 85% efficient while pulling 507W from the wall, then that would mean the system is pulling 431W from the PSU.
Therefore, a quality-made 450W power supply would be plenty for that.
Now the 7970:
With one 7970 under full load, their power supply pulled 355W from the wall outlet. As before, their CPU was idling, so let's add 200W again which makes the PSU pulling 555W from the wall outlet if both the 7970 and the CPU are under maximum load simultaneously. If the PSU is 85% efficient while pulling 555W from the wall outlet, then that means the system is pulling 472W from the PSU.
Therefore, a quality-made 500W power supply would be plenty for this. However, there are more 520W and 550W quality-made power supplies than 500W quality-made power supplies.
So this is why a quality-made 750W power supply can be a huge waste of money. Even a quality-made 650W power supply could be a huge waste of money, especially if you think you'll never have more than one video card.