New PC problem

Hey all, recently just built a new PC and I've having some problems with it.

When I first assembled it, it had this strange issue of powering on for about 5-10 seconds and then shutting off and then powering on again, and so on. The motherboard would not post at all. Then magically it started working a day later and ran fine for about 2-3 days. The CPU was running at about 40 degrees celsius. After that 2-3 days, the same problems occured again. I've removed components 1 by one, trying different ram, powersupply, etc. There would be no video either, would there be anything that shows before a post? What could make the computer power up and then power down like this? Thanks!

Here are the specs:

Windows vista 64 bit

gigabyte GA-EP45-DS3R

4 gigs g-skill ram

Quad Q6600 2.4Gz

8800 GTS (320 meg)

700w powersupply (can't remember the brand off the top of my head)

I have 2 2 gig sticks, I tried with 1 of the 2 gig sticks in and with both of the 2 gig sticks in. I'll have to find a 1 gig stick and try it out. korgoroth

do u get post with just the one stick in? but from my experience with a recent Gigabyte board, id be updating your bios.

I do not get a post at all. The screen just stays black and there is not video output. It was posting and running windows before but not anymore =/. Hopefully I can get it to post with 1 gig and then update the bios. Anyone else have any suggestions (will not be able to check until tomorrow or the next day, comp is currently at someone else's house). korgoroth

do u get post with no ram inserted? If answer = NO, your motherboard is faulty.