I read somewhere that the 7770 when overclocked consumes about 120-140W of electricity, which is just what the reference 7850 consumes. Is this true? If so, then is it worth buying the 7770 OC? I am looking at the Vapor-X version in particular.
It's not about the money. Heating and noise are bigger concerns for me. I understand that by getting these mid-tier cards some newly-released games would be unplayable, but that's okay. Currently I am just looking for a cool and quiet card that gives the most performance for 120W max and I would be playing games released around 2005.
So you are comparing a custom cooling solution to a reference design...
Of course the custom HD7770 is going to be better.
I dont really understand what you are wanting here. You look for heat and noise levels between different cards of the same GPU (So a Gigabyte 7850 vs an ASUS 7850), not across different GPU's entirely.