I think you got me wrong ! I didn't tell that a SATA (power or data) cable causes the MFT corruption. What I meant a loose SATA power cable can turn off the PC suddenly, that might be the cause on your side, though not sure, so I was asking. And do not over tighten any connections.
Can't computers start without hard drives?
And to clear things up, MFT corruption doesn't cause a PC to shut down on its own, so the problem may be related to a hardware failure. But time hasn't come yet to tell so obviously.
Could something which causes the corruption cause the shutting off also?
Edit: Random buzzing on my speakers and headphones (so it's not the audio device or front panel ports), motherboard dying possibly?