Motherboard, CPU, or PSU failure?

[James Devenberg]

Hello all.

After a power outage (and despite being plugged into an APC surge protector), my wife's PC will not boot. Not even to the BIOS. I've eliminated the GPU as an issue by a. testing the GPU in my PC, where it performed fine and b. trying to boot with the GPU removed and the monitor connected to the on board graphics. I also tried with several different monitors to make sure it wasn't a monitor issue simply not turning on.

Additionally, all the fans (including CPU cooler fan) will spin up and stay on and the LEDs on the fans and motherboard light up and will all remain on until you power it down, but it never actually outputs anything to the display or powers up the keyboard or mouse (no lights on either of them illuminate).

I also tried swapping in the RAM from a known good system and the PC still would not boot to the BIOS (or Windows).

Unfortunately, I cannot test to see if it is the CPU or the motherboard as my wife's PC has a 3470 which is LGA 1155 and I've got a 4690k which is LGA 1150.

If you sit there and power the PC on and off 50+ times it will *sometimes* boot and will stay on with no issues, but if windows forces a shut down via updates or it gets turned off in another way, its back to repeatedly turning it on and off hoping it will boot.

 

[panathas]

Have you tried resetting the CMOS? Also you should try testing this system with another PSU. In your case I'd say that it's 45-45 between the PSU and the motherboard. The remaining 10% is for your CPU. Try to reset the CMOS, use another PSU and then report back. Good luck.

 

[James Devenberg]

Have you tried resetting the CMOS? Also you should try testing this system with another PSU. In your case I'd say that it's 45-45 between the PSU and the motherboard. The remaining 10% is for your CPU. Try to reset the CMOS, use another PSU and then report back. Good luck.

Okay, I looked up my motherboard's manual (Asus P8Z77-m) and reset the CMOS to no avail (moved the jumper from pin 1-2 to pin 2-3 with power disconnected, waited 10 seconds, moved the jumper back to pins 1-2).

Then, because I didn't particularly feel like ripping the PSU out of the good computer (and having to redo all my cable management), I instead took the questionable power supply out of the non-functioning PC and hooked it up to the motherboard and CPU of the good computer (I couldn't run the GPU off of this PSU as it only had 1 PCIe plug and my GPU requires 2 PCIe plugs). I *was* able to boot my PC using the integrated graphics and the PSU from the non-functional computer. Does this rule out the PSU as the problem?

 

[panathas]

Yes that PSU seems fine. Can you post more info about that PSU (make, model number)? It seems that your motherboard got somehow damaged but you can do some more motherboard troubleshooting. Does your case have a PC speaker that beeps every time you power on that system? If it does, remove all the RAM sticks and try to boot. You should be able to hear some beep codes from that speaker. If you don't then that mobo is probably dead.

EDIT: Also for some additional testing, leave one RAM stick in the memory slots (you should try all of them) and remove every internal (drives, PCIe cards, etc) and external device (USB drives, keyboard, mouse, printer, etc) you may have. Then try to boot. A bad or damaged device connected to the mobo could prevent the system from posting.

 

[James Devenberg]

Its a corsair CX430. I do not have a case speaker. I'll try booting with 1 stick of known good ram, and try it in each slot. I'll also try booting with nothing attached.

 

[James Devenberg]

I just tried booting with nothing plugged into the motherboard (no drives, no GPU, no other cards) and no difference. Still won't boot to the bios (though all LEDs and fans still function). I also tried (still with no cards attached) a stick of known good RAM and tried it in all four slots of the motherboard. No change. Additionally, I tried the ram from the non-functioning PC in the known working PC and it booted just fine (I'm currently writing from the known working PC with the non-functioning PCs RAM in it).

EDIT: For clarity's sake, I did have a monitor plugged into the motherboard, but that was the only connected external device and the monitor and cable are known-working from testing with the known working PC.

 

[panathas]

OK you did a good job and covered every possible step. I'm afraid that the motherboard has failed, possibly because of the power outage. On top of that, this specific PSU model isn't very good. It has bad quality capacitors, that age very quickly and can cause stability/power issues by time. If you add a power outage to the mix, then things don't look good.

As a final note the CPU could also have failed but there is no way to test that without spare parts. Usually in similar situations the motherboard is damaged first and then the CPU but it's not extremely rare to see the opposite.

EDIT. Before drawing final conclusions try using another PSU on that system as the final step. What you did was somewhat parallel but you never know. After all that PSU's quality is questionable.

 

[James Devenberg]

So I tested it with a known good power supply and still no luck.

Went and picked up a 8600k, Mobo, cooler and RAM today. I'm going to give the wife my 4690k set up and upgrade my PC.