Black Screen + Buzzing Sound From Speakers, Sometimes Stuck At BIOS SCREEN

My PC operating on Windows 7 started sometimes getting stuck at bios screen with nothing to do but a restart which solved the problem since I guess about a month ago and resulted with a black screen and a buzzing sound from the speakers a few times while gaming, 2 of 3 of which are not demanding games for this pc by the way, within the last a few days I think after I updated my gpu driver to the latest one, I also heard a 1 second or less buzzing sound 2 times while gaming today.

I simultaneously ran Prime 95 blend cpu stress test and Kombustor gpu stress test and the PC froze after about half an hour.
I consider turning back to older gpu drivers and running a memory test next but I still don't have much of an idea what problem/s the pc may have.

The PC specs are as follows:
Gigabyte GA-P43-ES3G motherboard
LGA 771 to LGA 775 mode Xeon E5450 which used to run with 20% overclock but I turned it to stock settings I think about a year ago
Everest Rampage RMP-600-80P active pfc 80+ 600W psu
Nvidia Geforce 750 ti Galaxy OC 2GB edition running on 240 mhz core clock and 590 mhz memory clock overclock with MSI afterburner
4 800 MHz 2GB sticks of Kingston Ram
Samsung 850 Evo 500 GB SSD
External HDD
Bloody Gaming keyboard which becomes irresponsive if the pc asks whether Windows should do a normal startup after an abrupt reset
Bloody Gaming mouse

Please help if you can

The PC started to have stability problems before turning the cpu back to stock settings

Rustys said:

You may have done damage to the mother board and the CPU.

I agree with what other have stated on the other forums that you have posted this on time to replace.

Click to expand...

I used the cpu modded and overclocked for years so I think it's probably not that.