Q:

Dell PC's display goes off randomly

My PC's display turns off randomly and doesn't come back until I turn off my PC and then start it again. 
I have done the following things to resolve the issue, but they didn't work:

I initially thought it was a display driver issue, so I disabled the driver, but the issue persists.
I have replaced RAM several times, but it was of no use.
There's not a problem with the monitor because I have replaced it too.
I have unplugged all the connected devices/peripherals except hard disk, keyboard, and mouse.
I also reinstalled the OS.

The heatsink from one of the components on the motherboard is missing.

but I don't think it could have caused the issue because it was like that from the very beginning, but the issue has only occurred for a few days.
My PC's details are:
System:

CPU:

RAM:

Graphics:

EDIT: The issue has gone automatically and now the system is working fine.

A:

Clearly the problem is the blown capacitors. Capacitors are notorious for eventually going bad, especially when subjected to high temperatures over long periods of time. You should replace not only the capacitors which is a cheap fix if you're good at soldering*, but also the heatsink which is more expensive and possibly downright unobtainable because this is a Pentium 4 computer! I recommend retiring this "space heater" computer because it's not worth the time and money that would be required to fix it.
*What type of solder do I need when replacing capacitors?

