I would consider a power problem. try to remove or disable everything you can i.e. PCIX GPU (if you have one) PCI sound (same) all but boot drive. disconnect power from CD/DVD/Blueray/"insert updated format here" You may think "why? my PSU ran my previous board just fine" but things have now changed. You could have a power problem @ the switch caused by power pin installation mistakes like 180 polarity issue or just putting the wrong wire on the wrong pin. You can pull all of the pin power switch/reset/soft on, etc from front panel off the board and start the board by temporarily shorting the 2 pins that say "power on" with a screwdriver. Its a momentary contact circuit. NOT a switch so do NOT put a jumper on the pins as all this will do is start and restart and restart and restart or worse.
One thing I noticed about my board (same board) is that the main power plug (24 pin) does not lock in and can come out slightly causing strange behavior and lockups or no boot similar to what you describe. Aside of power problems or CPU compatibility.... pull out all of your memory modules leaving just one stick to boot. Normally bad memory will cause data corruption however, I have had issues where 1 bad stick of corsiar ddr2 mem in an earlier build would stop the board from posting. took it out and posts fine. Prior to that i had run prime99 to discover that 1 stick was bad and it got worse and worse until BSOD and no post.. One other good piece of advise: Instead of screwing around with a dangerous BIOS flash or update, go to gigabytes website and order the UPDATED or LATEST VERSION BIOS chip. It costs about 3$. and less to ship. I can not tell you with 100% certainty that the chip is not soldered in on this board as I am too lazy to pull my case open. But, most bios chips are just sitting in a little cradle and they come out easy. I did this with an earlier ASUS board due to flashing issues. It really is the best and safest way (IMO) to update BIOS. hope that helps you. hit me up