Gigabyte EP45 UD3P constantly reboots - no post

[lenf2]

Hello,
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?

 

[lenf2]

Sorry, that is a UD3P mobo not a UD3R

 

[aurzada]

It is the 8 Gb of RAM problem. Pull 4gigs, and I bet it works wonderfully.

 

[Siosin]

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.

Edit: Bah, didnt see how old this thread was.