Strange Problem - System will not boot

Paladine

Paladine

Paladine

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Joined
28 Oct 2006
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457
So, Christmas Eve, booted fiancee's PC and there was a horrible crackling noise followed by the smell of burnt electronics.

I immediately shut off all power to the rig - from the smell the PSU was fried and there were no obvious problems with the rest of the system (no burn marks, the burnt electrics smell was localised to the PSU.)

I went to the local store and bought a new PSU. Got home replugged everything in but the system would not boot. Graphics card seems to be getting power - red lights on the 8 pin power connectors when the PSU connectors are not plugged in and green when the are - which suggested to me that power is getting to the board otherwise the GPU would not have any power for the LEDs. But no beeps, drives do not spin up, optical drive has no power to open it and no fans power up.

So I figured it must be something to do with board - I tested the RAM and GPU in my own rig, no problems. I didn't test the CPU because both mine and my fiancee's have AIO liquid coolers attached so it would be a pain in the ass plus I figured a damaged CPU should not prevent the fans/drives from spinning up.

So I went out and bought a replacement motherboard today - fitted everything back together - still nothing. The GPU is getting power as before but no drives/fans spinning up.

Now I am not in a hurry to go out and buy a replacement CPU only to find out that that is not the problem either so I was wondering if anyone can confirm if a blown CPU can prevent the fans/drives from spinning up? Still no beeps and the manual for the motherboard is just terrible (Gigabyte 970A-DS3P) with zero troubleshooting info and I can't see any LEDs on the board to diagnose with either.

Could it be the power switch on the case? Is there a safe way to test the power switch? I plugged the reset switch leads into the Power Switch Connectors on the motherboard and held in the reset button to see if it would help but still nothing, I presume it would at least attempt to boot until I take my finger off the button - which makes me think it is not the power switch.

I am truly stumped, in the past whenever I have had issues at the very least the fans spin - to have no response at all is really confusing me.

Any help appreciated.
 
You can eliminate the power switch by manually shorting the 2 pins on the motherboard the case switch is connected to.

A PSU dying can take out any number of components, depending on the severity of the failure, but the most likely to get hit first are the things directly connected to the board. So GPU, RAM and CPU. A dead CPU will absolutely prevent the PC from booting so it would be my next thing to replace. The drives can be easily checked in another system.
 
ExRayTed said:
You can eliminate the power switch by manually shorting the 2 pins on the motherboard the case switch is connected to.

A PSU dying can take out any number of components, depending on the severity of the failure, but the most likely to get hit first are the things directly connected to the board. So GPU, RAM and CPU. A dead CPU will absolutely prevent the PC from booting so it would be my next thing to replace. The drives can be easily checked in another system.
Click to expand...

Yeah I just did the power pin short test as well still no response so not the switch.

GPU and RAM have been tested and are working in my system.

I know CPU can prevent boot but I have never known it to prevent the fans and drives from spinning up but then again I have only ever had 1 blown CPU (an AMD Barton Core that I screwed up a pencil mod on) and it was a very long time ago so I can't recall if the fans and drives span up when I tried to boot.

Given the motherboard and PSU are new, the RAM and GPU are tested and working and the power switch short didn't yield any results, I guess the only thing it could be now is the CPU - damaged drives would never stop a system from posting (or at least never have in the 25 years I have been building PCs).

Thanks for the reply.
 
when I killed my 3570k via a botched razor blade delid, the PC powered on and the fans spun.

Whether you could destroy a CPU more causing it not to do that, or whether different motherboards would react differently, I dont know.
 
Anyone else had a system where a blown CPU prevented the fans and drives from spinning up? Because I am still not sure the CPU is the problem and don't want to drop money on a new one only to find the problem is not fixed.
 
OK so I was right it wasn't the CPU. I decided to try one more thing before I left to buy the new CPU - I swapped out all the PSU cables (modular). When the old PSU blew I didn't swap out the cables (because it would have been a pain in the ass to redo the cable management) I just plugged the old PSU cables into the new PSU (since they were compatible).

So I unplugged them all and put in the new GPU cable turned the machine on fans started and speaker beeped. Added the new SATA power cables and it started fine - system is now booted and working.

So a healthy lesson I learned there - cost me a new motherboard that is the price of learning I guess. In 25 years I have never had PSU cables fail - not sure which cable was fried frankly I couldn't be bothered to test them I just trashed them all. I just knew it wasn't the CPU though, didn't add up that none of the fans or drives were spinning up.

I hope this thread is able to help others diagnose the same problem in the future. Thanks everyone for your responses.
 
Deathjester said:
What PSU was it?
Some PSUs have capacitors on cables.
Click to expand...

It was an OCZ 80 Bronze 600W - I did test the PCI-E power cables with the new PSU and they worked fine which is why I didn't bother swapping out the other cables - laziness really I didn't want to redo the cable management, lesson learned as I said.

The new PSU is a Corsair CS750M 80 Gold so it is a better PSU anyway.
 
Paladine said:
It was an OCZ 80 Bronze 600W - I did test the PCI-E power cables with the new PSU and they worked fine which is why I didn't bother swapping out the other cables - laziness really I didn't want to redo the cable management, lesson learned as I said.

The new PSU is a Corsair CS750M 80 Gold so it is a better PSU anyway.
Click to expand...

Ah right, it's entirely possible that the 24 pin layout is different on the Corsair.
 
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