Sorry to make another post as this is a follow on from my Motherboard return thread but I marked it as resolved and wanted to ask a further question and wasnt sure if anyone would bother looking at the post as it has the green tick. Anyway as I say, followng on. If power appears to be running through the motherboard eg, cpu fan/systrem fans/cd drive etc all have power is it likely that the motherboard is ok and has no issues?
the case connector wires can be so fiddly and seem almost impossible to get right, try removing them all except the power and case speaker, then try to reboot again. if you have got one of them wrong, it could be stuck in a loop constantly rebooting, never actually reaching the bios check just restarting over and over again.
this also checks the case switches are working ok (to test the power button, you could use a jumper instaed of the switch wires) holding in the power button for about 5 seconds should power down any ATX system. if not then maybe something is wrong with the PSU.
probably nothing there you havent tried but best i can offer short of sending the bits back.