Mining rig - burning smell when running - Please help!

[Check1]

PSU: Corsair AX 1200i (Platinum)
Motherboard: Asrock 970 Extreme 4
GPUs - 3 x Sapphire HD 7950
CPU: AMD Sempron 145

Just built mining rig with three GPUs on risers. After running the system under load for 2-3 minutes I experienced a burning smell. After 30 seconds the PSU fan stopped spinning. Despite this the full system was still running for about one minute before I turned the computer off at the PSU.

My first suspicion is the PSU as the fan stopped as the system was under load.

My second suspect is the GPUs as they were pretty warm after only two minutes usage at load. I felt that one or two of them might have been hotter than the third.

The third suspect is it was part of the motherboard.

Are there any common things which burn out on hardware at load? What would you suggest I do?

 

[Y0GI]

I would take out the PSU and sniff test it for the burned smell. If it does not smell burned, repeat with the video cards, MB, etc. until your nose finds the burned component. It should be obvious from what you described.

Yogi

 

[hunter315]

The GPUs would likely feel quite warm, quite warm to a person is only about 45C which is quite cool to a GPU. The PSU fan not spinning is suspicious though, so that would be my suspect, do what Y0GI suggests and sniff test the parts, that is the most reliable way to figure out if an electronic device has failed.

Also, can you describe the burning smell? Did it smell like something was hot, plastic was burning, or was it a disgusting burning smell? If it was the third, that would be the smell of magic smoke which would mean something either blew an IC or a cap.

 

[Check1]

Have an update.

We turned the machine on again and the PSU fan spun again during startup. However when we put it under load again the fan would still not spin.

In addition only two of the three GPUs were detected this time. GPUZ, Speccy and the mining program (CG Miner) only detected two cards. However fans were spinning on all three GPUs.

Could this be that the PSU is not correctly powering a GPU or is it more likely that one of the GPUs is faulty?

 

[Check1]

I would take out the PSU and sniff test it for the burned smell. If it does not smell burned, repeat with the video cards, MB, etc. until your nose finds the burned component. It should be obvious from what you described.

Yogi

We sniffed all parts and couldnt identify where the burning smell was coming from. The PSU smells fine now and the GPUs all smell identical and metallic.

 

[Check1]

The GPUs would likely feel quite warm, quite warm to a person is only about 45C which is quite cool to a GPU. The PSU fan not spinning is suspicious though, so that would be my suspect, do what Y0GI suggests and sniff test the parts, that is the most reliable way to figure out if an electronic device has failed.

Also, can you describe the burning smell? Did it smell like something was hot, plastic was burning, or was it a disgusting burning smell? If it was the third, that would be the smell of magic smoke which would mean something either blew an IC or a cap.

It was the 2nd one - like a plastic burning.