We must be missing something so have to think out loud.
We have a different motherboard with 2 different graphics cards, yet we get the same fault. Or do we? Do we still get the blinking cursor (which indicated a fault), or is now just nothing getting to the screen at all. FWIW the bios now has a UIFI interface which, I would have thought, be able to output to any modern monitor at a basic level. Am I correct in saying that you could see the bios when you first had the fault but cannot see it now. If you boot normally do you get the logon beep. If you boot with the Windows disc in the optical drive (and keep pressing a key while booting) does the drive light flash as it loads the Windows basic files. If so then at least that works.
If the HDMI lead is OK then the only other common denominator I can think of is the PSU. You say that the GPU works but is that when using the PSU in that computer.
Sorry for the questions mgsolidus but I want to be clear on what the situation now is.
We have a different motherboard with 2 different graphics cards, yet we get the same fault. Or do we? Do we still get the blinking cursor (which indicated a fault), or is now just nothing getting to the screen at all. FWIW the bios now has a UIFI interface which, I would have thought, be able to output to any modern monitor at a basic level. Am I correct in saying that you could see the bios when you first had the fault but cannot see it now. If you boot normally do you get the logon beep. If you boot with the Windows disc in the optical drive (and keep pressing a key while booting) does the drive light flash as it loads the Windows basic files. If so then at least that works.
If the HDMI lead is OK then the only other common denominator I can think of is the PSU. You say that the GPU works but is that when using the PSU in that computer.
Sorry for the questions mgsolidus but I want to be clear on what the situation now is.