PC powers on for 1 sec. then shuts off - Gigabyte P55-UD4P, i5 750 (*SOLVED!*)

[DylanFromCanada]

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?

[Meridian]

Can I just check that when you cleared CMOS the PSU was disconnected from the mains? And you kept the jumper over for at least fifteen seconds? And did you take all the RAM out, and then try one stick? If not, try that. Finally, try powering up the m/b with nothing connected except the CPU: no RAM no gfx. Do you get BIOS beeps?


You've tried pretty much everything else I can think of except one thing: leave the m/b disconnected from everything, including out of the case, for at least a day, and then try it again in the case with just RAM, CPU and gfx. If that fails, I'd guess that you've borked the m/b.


M

[DylanFromCanada]

Can I just check that when you cleared CMOS the PSU was disconnected from the mains? And you kept the jumper over for at least fifteen seconds? And did you take all the RAM out, and then try one stick? If not, try that. Finally, try powering up the m/b with nothing connected except the CPU: no RAM no gfx. Do you get BIOS beeps?


You've tried pretty much everything else I can think of except one thing: leave the m/b disconnected from everything, including out of the case, for at least a day, and then try it again in the case with just RAM, CPU and gfx. If that fails, I'd guess that you've borked the m/b.


M

Yes no power supply and kept jumper on for 10-15 mins along with the battery removed just to make sure.

I've already tried one stick of RAM with no luck.

Tried powering up with just motherboard and CPU. Same thing PHASE lights flash and fans start for less than 1 sec.

I tried again with my other power supply but it only has a 4 pin connection for the CPU power plug. It basically starts to power up to but the PHASE LED lights don't even light up.

I don't think it means anything but trying to power up without the six pin CPU power connected puts the motherboard in a loop of powering up for 1 sec and then shutting off... repeating ever few seconds.

I'm guessing (hoping) that it could be the new PSU is faulty. I have a volt meter but I don't know how to use it for testing the power output on 6 pin cable.

Also when the 1,2,3,4 PHASE LED lights turn on for the 1 sec (or less) they are 1 (Green), 2 (Green), 3 (Orange/Yellow), 4 (Red).

[MrBlack]

sounds like it's down to the CPU - what does the warranty on it say?

[Meridian]

PSU is definitely possible as your test 550W would struggle to spark up that rig unless it was absolutely top notch. I'm not inclined to believe that the CPU is at fault as that is VERY rare. After PSU I'd go for the motherboard.

(BTW, what I meant about the RAM was to remove it all, then put one stick back. It's to check for dodgy RAM sockets. But the info from trying without it suggests that point is moot)

If you aren't getting BIOS beeps for RAM not in place, then the POST is not getting past checking the CPU. Sadly, the only way forward now is to try the CPU in another rig, and then the PSU in another rig. Note that the latter is risky, as is may blow rig #2 if it is the problem.


M

[DylanFromCanada]

I believe I found the culprit, the Gigabyte P55-UD4P motherboard.

How did I come to this conclusion. The fizz sound followed by a puff of smoke was a hint.

I tried resetting CPU and switched on the power this time the motherboard didn't instantly shut off but I heard a fizz followed by smoke and that awful smell we all fear.

It was hard to see but it looks like 2 solder joints have become fused. It was on a chip under the heatpipe/heatsink that surrounds the CPU.

There are a bunch of these chips in direct contact with the motherboard heatsink/heatpipe. See photo below under the blue/white heatsink at the top of this photo.



Now it's time to check and see what Gigabytes warranty is on it's motherboards. I bought this about 3-4 months ago.

It the mean time I can't wait for a warranty replacement or repair because I'm sure these weeks or months to complete.

Any suggestions on a replacement 1156 motherboard for Intel i5? This was my first Gigabyte motherboard I've always been an ASUS guy.

[Meridian]

Bad luck on the board, but it is always so much better when you know what the problem actually is. Can't help you with a recommendation though. The choice of motherboards seems to have thinned out over the years leaving Asus, Gigabyte and EVGA (and they only do a couple of models) with most of the market at this level. I've never liked Gigabyte, although I have one (which I don't like), and a string of bad Asus boards put me off them (hence the Gigabyte). I've always wanted to try EVGA, but stock tends to be erratic over here.


M

[Mickey21]

Likely a fault in an isolated case. I wouldnt worry about trying another one. There are always bad ones in the bunch. Gigabyte used to be at the bottom of my choices but they do represent one of the better manufacturers today. Personally I would choose either a Gigabyte/Asus/EVGA model without too much worry other than features and costs...

Was likely just a power surge in your case and if you dont have a quality power supply, consider a replacement. What failed was the VRM's by the sound of it. It might not have been the motherboards fault it received a jolt of power it couldnt handle. Dont be too quick to judge.