My pc crashed, and I don’t know how to identify which part of the hardware is beyond repair.

Symptoms:
1.) BSOD - Black and blue screens of death.
2.) Memtest hang (played from UBUNTU.)
3.) sudden restarts
4.) blue screens, if successful loading of windows.

Additional Info:
1.) could not disable automatic restart, I can barely get the chance to do so, because of restarts, which possibly can damage the motherboard/ram/HD; thus I have decided not to turn it on(pc). . . yet

I reckon that the RAM must be broken and needs to be replaced but I’m still not sure, I have asked a second opinion from my brother but I don’t think it is very reliable.

So I wonder if any of you guys know any general diagnostic procedures to trace the cause(s) of the crash. So that I can decided what to replace. I’m sure my problem is purely hardware and has nothing to do with the OS.

I know a little with hardware troubleshooting but it’s not much and it’ll pain me even more if I don’t do something with the situation. So far this is the only information I know about the problem.

So, suggestions anyone?