Motherboards Unplugging 12V while PC is On

Would unplugging the 4-pin 12V square-looking PSU cable from the motherboard while the PC is on cause some sort of irreversible damage?

The PC turns on just fine but doesn't post anymore. Also, if it's dead, would it be safe to pull out and still use the NVIDIA PCI-E card and the SATA HDD transplanted onto another PC?

 

And why would you want to remove this while your computer is running, exactly?
To answer your other question, you can transplant parts, yes. With the hard drive, I'd strongly recommend doing a fresh install to avoid any driver issues.

 

It was kind of an accident caused by an idiot cousin of mine. Is the motherboard or PSU damaged, probably?

 

I take it before this accident occurred, the computer booted just fine? If yes, then there's your answer. Tell your cousin he can buy you another motherboard and possibly CPU and RAM. He should probably stop rooting around in computer cases from now on.

 

Is this the extra 4 pin from 24pin, or the 4pin by the CPU socket? I had the former happen to an older motherboard. The 4 pin was always a little loose, and the cable had to stretch across the board, so after a while of running, it came loose. The system kept going until I shut down, and then would not boot. Fried the motherboard. CPU etc was fine.

If it is the latter, then you may have a dead CPU, as well as a dead mobo and RAM, like the padre says.

 

The 12v 4's are usually silly short cables, especially on non-modular PSUs, I'd recommend picking up a little extension cable to be on the safe side in the future.

I buy mine from Maplin, as the shop assistants keep reminding me, it's waaaaay overpriced, but it's there and it's handy. I think it was 2.99 I paid for the extension cable and it was in the aisle along with the fans/system blowers/cables. Just a hint.

 

Plugging in anything or removing anything, including fans while the system is running is going to cause an issue.

 

Try unplugging/unsocketing everything, reseating it and a new PSU. Did that to a PC i was replacing a HDD on (Compaq POS, P4 plug was loose when I got it (didn't notice), fell out during a windows 7 install!)

System booted fine afterwards. Guess I was lucky though!

Done the fan unplug+replug many times without issue, same with SATA, without issue. Then again I go for premium boards/server boards. Server boards are designed for hotswap

 

Have you tried just resetting the BIOS by clearing the CMOS?

I don't see why losing power should suddenly cause irreparable damage?

 

It might have done but I've certainly unplugged when the system has been on many times....