Computer Freezing at BIOS splash screen

Hello and thanks for any help in advance. I have a home built Phenom II X4 2.7 (Comp. Specs on my profile) which I was using an ASUS M4A785-M MB with. Last week my computer started freezing up at the BIOS screen. I removed all RAM and checked for diagnostic beeps. No beeps. I put one stick of ram in at a time, taking the ram out and putting in a different stick each time. It still did the same thing. I removed all cards and used the on board and it did the same thing. I bought and installed a new 600 Watt thermaltake and it still did the same thing. I checked for possible grounding issues, there were none. Today I took the RAM and MB to be bench tested and both were OK. I had ordered and received a new MSi 785GT-E63 MB and installed that tonight. I set everything up and installed everything properly and double then triple checked all connections and hardware. I powered up and it did the same thing, only this time it doesnt make it to the BIOS screen, it freezes at the MSi splash screen before the BIOS screen. Before I installed this MB I took it and had it bench tested to make sure it was good before I did anything further. Since installing I have gone through all the same things as mentioned above with the ASUS and it does nothing, just freezes. I am at a total loss for an explanation. Anyone have any other things I might try? Thanks
Jeff