I have what seems to be a common problem, but no solution. I have the following system:
Gigabyte EP45 UD3R Motherboard
Intel Q9550 processor
4x2GB RAm for 8GB total
Seagate 640GB Sata HDD
Nvidia GeForce 9800GT SLI Graphics Card
FSP 700 watt PSU
Zerotherm NV120 HSF
M-Audio Delta 1010LT Audio input card
Moded AT Server case - all steel - 1'x2'x3' on rollers, swing out sides and front panel
My problem is that the unit constantly reboots and gives no postafter power up. I have tested the RAM, replaced the PSU unplugged all non-essential equipment, made certain that both the 24 pin 12v and the 8 pin CPU power connector are connected properly, I have reset the cmos and the problem persists.
I have found one item of particular interest, the unit only reboots when the CPU 8 pin power line is plugged in, unplug it and everything goes to normal (except of course it won't boot up without the processor). Additionally the CPU fan is a 3 pin plug and the Mobo has a 4 pin header, and the fan will NOT come on when plugged into the header, but will come on when it is plugged into the SysFan1 header.
Heating is not a problem as I have 9 fans in the box, and there is not enough time for the processor to get hot.
The rebooting continues endlessly.
Any suggestions? Is this the motherboard or the processor?
Curious to see if the OP ever figured this out. I have the same board and it appears the ram slots are dying. I can get the system to boot with only 1 stick of ram in slot 1, everything else hangs.
That said, once the system starts up its a crap shoot for the system to randomly reboot. Usually seems to happen when say running a video clip from youtube. Problem has been going on for months but just recently wouldn't boot at all unless just 1 stick was in slot1. Thought it was a vid card or psu problem.