Black Screen On Boot Up

I start my computer and I see the first BIOS page, then it becomes black. This happens all the way through the BIOS settings including the Windows XP loading page. Once I get to desktop I might see it for 1-2 seconds and then it goes black again. After this is generally stays black permidently. The screen is still on and has power to it, it is not in stand by as it is still green in colour.

I bought a new graphics card, stupidly, which was not the problem as it still seems to happen. (thus the reason I am not posting in the graphics section). Have you guys got any idea what else it could be? RAM? PSU? CPU?

Any help would be appriciated. Also I have tried to load it in safe mode but it goes black in the safe mode aswell. So I really cant do anything, it happened randomly, it was not like I downloaded something like a virus which made it happen, it just suddenly happened.