So you are getting nothing on the display?
Is monitor cable connected to mobo or GPU? (dumb question but it needs to be asked)
I would be dismantling the whole thing and reassembling on a piece of cardboard.
Only connect the bare essentials to get a signal on the screen, so at this stage not even a keyboard/mouse, one drive, no DVD, one RAM stick, the GPU, that sort of thing.
Once you get the screen to show anything, then you can add more components to the test bed.
Is monitor cable connected to mobo or GPU? (dumb question but it needs to be asked)
I would be dismantling the whole thing and reassembling on a piece of cardboard.
Only connect the bare essentials to get a signal on the screen, so at this stage not even a keyboard/mouse, one drive, no DVD, one RAM stick, the GPU, that sort of thing.
Once you get the screen to show anything, then you can add more components to the test bed.