PC won't POST or BIOS but fans spin up then turn off

Jas1222

Jas1222

Jas1222

Associate
Joined
4 Jan 2012
Posts
275
I've had my rig since 2012 now and it's been working fine up until now. When booting it one day it wouldn't recognise my SSD (but I've had that problem before) and I usually fix that by doing a few cold boot cycles.

However when turning my PSU on and off again I noticed a burning smell and when pressing the power button. The CPU fan and case fans spin up for about 3 seconds and then turn off, turn back on again and the cycle repeats but there is no BIOS or any display on the screen.

I've tried:
- New power supply
- New motherboard
- Reseating all the RAM, and in different slot combinations
- Taking the GPU out and just using the on-board GPU - Resetting the CMOS battery
- Taking my after-market cooler off and just using the stock cooler (while replacing the thermal paste)
- External build (just the CPU, CPU fan, PSU, 1 RAM stick, 8-pin CPU power cable, 24-pin motherboard cable) plugged together (both with the old and new PSU and motherboard)
- Checking the capacitors and stand-offs (nothing wrong)

The only progress I've seen is when I reset the CMOS battery the fans spin for about 5 seconds longer but then stop, then start to spin up again. The LEDs on the motherboard all work fine. I don't know what else to try apart from buying a new CPU and RAM stick.

I don't have a motherboard speaker to plug in (I've never heard it beep even when it was working fine)

Any help would be appreciated.
 
I've had no USBs plugged into the motherboard when testing it, I haven't been able to memtest the RAM since I don't have another rig I could test it under but I may pick up a cheap 2GB stick during my lunch (that's the next big culprit I think).

Really frustrating since I now have to return the PSU and motherboard.
 
PSU works fine. I bought a speaker for the motherboard yet I'm getting no beeps at all. It spins for longer now but still no video output and then it just dies, and then the fans restart spinning.
 
Have you tried getting it to boot with no RAM at all? that should cause 3 beeps indicating that no RAM is installed. If it doesn't do anything then the problem lies elsewhere.
 
JonSmith said:
Have you tried getting it to boot with no RAM at all? that should cause 3 beeps indicating that no RAM is installed. If it doesn't do anything then the problem lies elsewhere.
Click to expand...

I haven't tried that, I'll give it ago tonight. If it still doesn't beep then surely it must be the CPU?
 
sounds simple but did you do a full cmos clear? leave mb battery out a good 30 minutes then pop back in and try
 
wazza300 said:
sounds simple but did you do a full cmos clear? leave mb battery out a good 30 minutes then pop back in and try
Click to expand...

I left it out for 20 minutes but that didn't do much good.

I tried starting it without any RAM installed and the motherboard finally gave 1 long beep and 2 short beeps which rules out the RAM. Looks like the CPU is the main offender here. Have to downgrade from a i5 2500k to i3 3220 =[

I'll confirm and post back tomorrow evening if that's fixed it.
 
So tried old motherboard, new PSU, new CPU, new RAM. Still doesn't work.

I bent some of the pins on the new motherboard so I can't really test the entire new build out. Might have to just order ANOTHER one.

Pre-bent pins: I tried new mobo, new PSU, old CPU, old RAM.

I've tried different plugs and a different power cable. This is becoming ridiculous now.
 
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