Hi I have a very weird computer problem, basically the computer screen will not start like it used to. When i press the power button everything in the pc turns on it seems but the monitor screen is black. I tested the monitor at a friends house and it worked perfectly, i have also bought a brand new gfx card and the problem persists. I hope someone can help me because I am at a loss and have no clue what to do next. When i switch the pc on, everything inside seems normal, I have checked and rechecked all cables and connections. Please help me, how can i find whats causing this?