There is an gap slot on my Compaq D510 motherboard but there is no sign of it in the bios. When I fit a card in the slot the machine will not boot. Does this mean that the slot is not connected to the board?
It should be compatible. Has it been tested in another system to make sure that it's working properly?
No I have not tried testing the card in another machine but I may have to resort to this. I should add that I have installed the appropriate driver from the hp site. Should not the machine boot even if the card is faulty as long as the bios is unchanged and the monitor is still connected directly to the motherboard?
If the AGP card is installed, then the monitor has to be connected to it. That system doesn't support both the on-board GPU and the AGP card. As soon as the AGP card is installed, the on-board GPU automatically is disabled.