Potential mobo failiure: Need advice.

Alactric

Hey lads, I was wondering if any of you could help me. I’m having trouble diagnosing a problem with my PC. I’ve narrowed it down to either the PSU or the MOBO but I’m really not sure.

The machine worked fine up until 2 weeks ago, when I started getting this loud grinding noise on start-up that would last until the machine was fully booted, I thought that maybe it was some case fan going haywire and didn’t think it was a big deal.

The Grinding noise was a regular occurrence until Monday, where the machine failed to boot at all. No PSU fan start up, no blinking lights, no beeping, nothing, totally dead. So I looked into the problem, came to the conclusion that the PSU must be the problem. Apparently the PSU fan can create a grinding noise when it’s dying, so I put two and two together and assumed the PSU was dead.

So I went to Maplins and got a new PSU, same wattage and everything and hooked it up. Surprisingly, the brand new PSU wouldn’t power on either. So I checked that the 24 pin connector was in, making extra sure that the detachable 4 pin was in, and I double checked the 8 pin secondary power supply was secure and still nothing. So if the new PSU wouldn’t work, this got me thinking that maybe the old power supply was actually fine?

Since a didn’t have a voltmeter or even another desktop to test the PSU’s I resorted to the old paper clip test (even though you probably wouldn’t recommend it) and shorted the green and black wires in the 20 pin, and sure enough BOTH PSUs started up fine.

So…the problem absolutely has to be the motherboard right? What else could it be? Strangely, I never encountered any of the tell-tale signs of the mother board going bad, no random shutdowns, no weird graphical glitches and no problems with any SATA or USB enabled devices. I’m really confused to be honest, I wouldn’t fancy my chances of RMA’ing something at this time of year, god knows when it would come back, any ideas?


Edit: Now that I think of it, the Ethernet port never worked properly and the front panel USB 3.0 has always taken a while to register stuff, but I always thought that those were just driver issues…

edit 2: Failiure ><

game4it70

It does sound like the mobo.Did you check it for any physical damage like blown caps or scorch marks?
The noise is strange but could it have been coil whine from the Gpu?

A dead Gpu could also cause your problem.I would strip the rig down to just mobo/cpu and psu to see if that gives any signs of life.Even if you dont have onboard gfx it would help to rule out your Gpu.

Alactric

game4it70 wrote: »

It does sound like the mobo.Did you check it for any physical damage like blown caps or scorch marks?
The noise is strange but could it have been coil whine from the Gpu?

A dead Gpu could also cause your problem.I would strip the rig down to just mobo/cpu and psu to see if that gives any signs of life.Even if you dont have onboard gfx it would help to rule out your Gpu.

Thanks for the reply.

I have ruled out the GPU. When I was testing the power it wasn't even in the PCIE. Also, it's just not very likely that's the problem, it's performed flawlessly since I got it in June. I also have on-board Intel HD gfx, so that would boot in the absence of my main card.

I didn't notice any physical damage to the board, then again I'm clearly not an authority on such things, but there was nothing visibly wrong as far as I could tell.

It's looking more and more likely that it's the mobo though, I couldn't possibly have two bad PSU's that boot when shorted, but don't boot when hooked up to the board

game4it70

Could there be anything causing a short? Again another reason to try it outside of case.

One other thing which is very unlikely is that the case power on switch has broken.

As you said yourself it really looks like mobo but normally when they fail you still have some form of signs of life.

Alactric

game4it70 wrote: »

Could there be anything causing a short? Again another reason to try it outside of case.

One other thing which is very unlikely is that the case power on switch has broken.

As you said yourself it really looks like mobo but normally when they fail you still have some form of signs of life.

the power on switch? you mean the one on the PSU or the front panel?

I'll definitely try it outside of the case though. Maybe the back brace for the cpu cooler is doing something? Haven't a clue at this stage :rolleyes:

game4it70

Yes the case front panel is what i meant.