You'll be interested to know that I have windows working again however if I plug any graphics cards into my computer it just stays at a black screen, I tested with 2 graphics cards the one that was already in there and a spare one that definitely worked
the black screen when trying a gpu could down to a bios setting. Make sure secure boot isn't enabled and the bios is set to legacy. Look under the 'Peripherals' section and you should see 'Initial display output', this is where you set what the machine uses for graphics.
I doubt that both gpu's are faulty and it's probably down to a setting but just in case is it possible for you to test the cards in a friends machine?
To be honest I've never heard of anything like this. I would have thought it was down the bios flash but it's the same with both bios's, old and new. Have you checked all connections so that they are tight and nothing is loose?
I'm not exactly sure. If the slots were dead then it would account for no picture but when the gpu is actually running and still no picture then i'm unsure what the issue may be. I will have to do some research and get back to you.
can you try clearing the bios. You can do this a number of ways although usually the easiest is to carefully remove the bios battery for a minute. When the system boots back up go back into the bios straight away and load 'Bios optimal default setting'. Once you've done that try the graphics card again.
My friend was saying that after he had flashed the bios he had to change cables but he was using a vga cable and changed to a dvi. Do you have any different cables to try anyway?
I'm still trying to find out what may have occurred with your machine but no one seems to have any ideas apart from what I've just suggested. I will keep looking tho..