|"my PSU has a 525 wattage"|
Wattage is only one of the many specs that need to be considered when selecting a PSU. Amperage on the +12v rail is extremely important, so is having active PFC & an 80 Plus efficiency rating.
"I need a 12v current rating of 40A, while my current 12v rating is MUCH lower. I think it was about about 8A."
I don't know where you came up with the 40A requirement, but the HD 7770 only requires about 20W more than the HD 5670 & that only amounts to an additional 1.7A. However, if your PSU only has 8A on the +12v rail, it's either extremely outdated or a low end piece of junk. Either way, it should be replaced ASAP. How about posting the make/model of your PSU so that we can verify the specs?
This Corsair 430W PSU (on sale for $20 after rebate) should be more than sufficient for your system & it's an excellent unit:
Have a look at this HD 5670 vs HD 7770 comparison:
Also have a look at these wattage numbers for systems with various video cards. An entire system under full load with an HD 7770 only consumes 250W:
message edited by riider