So one day, the PSU in the machine I was working with decided to blow up. Yes, I heard a pop, and a strong burnt smell.
So what happened? What caused it? How can I prevent it?
- The PC was NOT running, it was turned OFF
- It was connected to a power outlet
- The PSU was turned on
- There was this USB fan attached, and it was kept running
- The PSU was more than 5 years old
- USB Legacy support has been turned on in the BIOS to provide power to USB socket even when machine is turned off
So, I was afraid that the whole motherboard was fried, I went to buy a new PSU to try things out. As soon as I fitted the new PSU, everything is fine again.
I noticed that no cooling fans were running while the PC was off. CPU and Case Fans were off obviously. However the PSU's own cooling fan was not on.
Could it be that, the tiny USB fan, that draws electricity from the PSU, overheat the PSU since the cooling fan was off?
It sounds bizarre but that is the only reason I could think of. If so, would it be a bad idea to keep USB devices powered and running while having the machine turned off?