So I got a used pc and for the last two months it was working mostly fine until (dumb me) tried changing the settings in the BIOS to (Core Unlocker + Overclocking of +4% to try), before this I usually used the Core Unlocker feature alone (though every so often it disabled itself for no apparent reason).
Things I noticed:
The system starts, and the fans start spinning, but there is no beep and no screen output.
The PSU fan makes a strange sound but stops after a while (it did this before, but I ignored until now).
The CPU Socket is slightly dusty (but it seems that the CPU still did contact in the past).
MB:Asus M578L-M LX3 AM3+
CPU: Amd Athlon II 160u
RAM: 4GB Kingston DDR3 1333MHz (2x2GB)
PSU: BRB ATX 550w X 24 P 1S
What I tried:
Removing RAM Sticks and replacing both RAM sticks with a single 2GB module (in both positions).
Connecting system speaker to hear error codes, but no error codes.
Removed RAM and CPU to hear error codes, but nothing.
Removed CMOS Battery for 30s to [hopefully] clear all settings.
Tried shorting the pins instructed in the motherboard manual (I may have done it incorrectly, though).
I was thinking of getting a multimeter to check PSU like what it said the README, and cleaning the CPU Socket with compress air. Thanks guys for your support