I removed my graphics card to make way for a new network card in the PCI slot alongside the AGP slot. When I replaced the graphics card, I found there was no picture to the monitor, so I presumed I'd broken the graphics card.
I tried a new graphics card but there was still no picture. However, I noticed that when I disconnected the monitor from either graphics card, it flashed a message that a cable was disconnected. I don't get this message when the monitor cable is connected to one of the cards.
Next I reset the clear CMOS jumper, to no avail, and tried booting the system without any card in place, just to see if Windows had cleared the problem itself and could then re-intall it. Still no joy.
I don't believe I've disturbed the RAM because it's sited quite a way from the AGP slot.
The motherboard is a MSI 875P MS-6758 (v2.X) ATX.
Clearly, I'm writing this on my backup computer! Any advice would be most appreciated.