Radeon HD 6970 vs. Radeon HD 7750

[Hellspawn1791]

Background info: bought the 6970 to replace the 7750. Online I found info that the 6970 should outperform the 7750. However, the 7750 is getting way better benchmarks. I bought the 7750 due to its price to performance ratio since I can't afford a $200+ card.
Note: I can play most games with 7750 on ultra, but I can't do the same with the 6970 even though it should as far as I'm aware of. I do only have a 530W PSU and the 6970 specs say it needs 550W minimum. Would that be the culprit?

The question: which one should be better in theory?

6970 specs:
http://www.powercolor.com/us/products_features.asp?id=3...

7750 specs:
http://www.hisdigital.com/un/product2-682.shtml

 

[angelice]

What is the brand of your power supply, I know for a fact that a 6970 will out perform a 7770, so something is obviously wrong, and power supply could very likely be the issue.

 

[Hellspawn1791]

Yeah the power supply is the problem. I found out it needs 550 and I have 530.

 

[angelice]

honestly if it is a good brand power supply that shouldn't be an issue what is the brand model and age of the power supply.