When you over-tweaked your computer sometimes a hardware fails. Most of the time it's the Memory, sometimes Video Card, and sometimes the saddest thing of all is the Motherboard, but sometimes Hard-disk or other parts of the computer.
When you start your computer and the Blue-Screen (that's what computer technicians call it) appears are most cases the faulty hardware is the Memory.
When the Blue-Screen appears, the computer is telling you that there is something wrong in the computers parts or hardware. The computer will not tell you exactly what's wrong because it is written in codes and even it is written in codes it is not telling the viewer what exactly is the problem.
Have you ever heard of the saying Trial and Error. We call it too that way because we do it that way too. We replace each part of the computer one-by-one. In other words, we replace each part of the computer and turning it on and off to see what part of the computer is the source of the Blue-Screen