I keep my computer in a cabinet, and I'm thinking of venting the cabinet with a 92mm or 120mm fan. I've got a few lying around, but I'd need to plug it in to a wall outlet. Should I just use an AC->DC ...

It's easy to think that the CPU or graphics card are the beating heart of your gaming PC, but they wouldn't get very far without sufficient cooling - unless you want a very expensive and ineffective ...