I can't get my motherboard to POST. I power on and the 4 PHASE LED light up (all 4) and the CPU & GPU fans start to spin for about 1 second and then it shuts off.
I've had the motherboard, CPU and RAM running for about 4 months. I recently upgraded the stock heatsink to Noctua NNH-U12P SE2, PSU to OCZ ModXStream Pro 700W ATX 20/24PIN, along with case Coolermaster Cm 690 II Advanced.
Gigabyte P55-UD4P (MB REV: 1.0, BIOS Ver F9)
Intel i5 750 2.67 GHz
G.SKILL Ripjaws F3-12800CL7D-4GBRH (2x2GB)
OCZ ModXStream Pro 700W ATX 20/24PIN
EVGA Nvidia 7800GT
Windows 7 Home Premium 64 Bit
I recently replaced stock heatsink with noctua so I cleaned CPU headspreader and reset with noctua using small amount of thermal paste, installed motherboard in new case along with OCZ 700W psu.
Everthing booted up fine with just the bare min. of attached devices, 2 640GB SATA2 hard drives running RAID 0.
Once it booted I checked temps and everything looked great 20-30 degrees celcius cooler than stock when running Prime95.
I then connected the rest of the harddrives (2 more 7200 RPM sata2, 1 OCZ SSD, 2 sata2 DVDRW drives, and the case fans.
Everything ran fine did the stress testing, temperatures were 30-40C.
I used the ASUS Quick Boost to bump the CPU to 3.0 Ghz ran stress test, then bumped it to the next step 3.8 Ghz and everything booted fine and tested ok.
I then moved the OC CPU back down to 3.0Ghz and re-enabled Turbo. The computer booted up and during a Prime95 stress test the computer powered off. Temps were about 55-60C when this happened. With stock heatsink and Turbo enabled temps would reach 70C.
I then tried booting again and the problem started. I was able to get the computer to boot a couple times by disconnected some of the extra hard drives and DVDRW drives. It eventually shutoff again and I haven't been able to get the motherboard to POST.
Here is what I've tried:
Disconnected and reset (GPU, CPU, RAM, power connectors)
Tried one stick of RAM
Cleared CMOS (jumper), removed battery
Removed M/B and ran outside case
Tested PSU (paperclip Green to Ground) It powered on
Tried my old PSU 550W, same result (doesn't have 8 pin CPU power conn.)
PC speaker connected (no sound, power on only lasts 1 second)
Looked for possible motherboard shorts or blown capacitors/transistors
Any ideas?