What would happen if there was at least 3 CPU Socket Pins(LGA775)bent?

I've never had any bent pins on an LGA775 but I will say that if I noticed some during a build I would not even bother mounting the processor.

Believe it or not, with a small flathead screwdriver, you can bend them back. Like an idiot, I bent about 5 on my 750i and I just used a small flathead screwdriver and bent them back VERY slowly and VERY carefully and to this day, it works amazingly. If you left the pins bent out of shape, it MAY work, but 99.9% chance it will just not POST. Happened to me as well, if you can exchange the board, do so, if not, then just be REALLY careful and bend the pins back, it will work as if it were never bent. The only thing I would be concerned about is hurting the mobo, processors are pretty resilient, but even then, in this case, I wouldn't worry at all. Hope this answers your question ^.~