I find the usual reviews that tell me what said video cards draw in idle and under load. That's where I look at the power supply and check that any of the rails I want to see no more than 50% of the capacity in use. Sure you can probably push that up to 75 or 80% but as we do that we are eating into the lifespan of the PSU.
Not only that, the usual Amperes and total Watts are only when new and even then tend to be overstated.
-> But those cards are all in the same tier range so I'd not change the card once I got that.
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html pegs the 7770 lower in the ranking so I'd use this link to find the best for the money.
I have a quick question about this power supply. I have just ordered an i5 3570 non k along with other gaming basics 8gb of ram etc. I recently brought a coolermaster elite 430 with a elite power 500w power supply.
I am planning on getting either a gtx 660 non ti, a 650 ti boost when that is out, or a 2gb 7770 depending on how far I will be able to stretch my budget. My question is will this power supply be able to run these graphics cards? Or will I have to send this back and get a different one? Later on I will crossfire/SLI and will change the power supply then.