No Display ! if you have no display and your Pc tries to boot

Here is brief summary of thing's you can try

Check Pc , monitor have power supply and Vga cable connections are good
Temporary disable power management in your cmos and monitor to prove this is not the cause.
Try your Pc with a different monitor if possible or try your monitor with a laptop .this will establish if the problem is your monitor or a problem with the pc.
If it is proven to be a pc problem do you hear any bios beeps from pc speaker on start-up i.e. 1 long 2 or 3 short beeps If so then turn off pc and remove case cover with a anti-static wrist strap remove card Check you are inserting the correct type of card for the slot type (some AGP 4x slots will only accept 1.5 volt cards and not previous 3.3 volt cards) clean card connections with a pencil eraser and re-insert card making sure it seats fully home in its slot .Replace cover.
If problem persists check the vga display adaptor fan is running when system tries to boot (if fitted) and the card is not overheating due to poor case ventilation . (leave off see if it will boot up the display from a cold boot and thus prove a heat problem)
If this does not work there may be a conflict between a addin Pci card and the AGP card which are sharing a system resource. Remove all unnecessary cards not needed to boot pc and check cmos is set to bios plug and play configuration and add the cards back to system one by one testing start-up after each card added . Either the problem will go away as the cmos reconfigures each card or the conflicting card will prevent display working properly again ,if so check configuration of card against manufactures info or seek their advise.
If you still have the problem see if you can try the card in another pc .This will prove if the problem is related to the card or the computer.
If it is found to be the card check the configuration settings of the card against manufacturer info or you may have a corrupt Vga bios see if you can restore the bios with a bios programming floppy disk from the adaptors manufacturer . If this does not solve the problem the card is likely to be faulty.
If it is found to be the Pc .Check all motherboard configuration and jumpers are correct check especially AGP Bus speed and Voltage setting.
If all this fails it is possible it is the motherboard its self . is faulty .Recommend it is checked out by a expert.

I hope this helps .If you are not confident with the tasks above .Leave it to a expert !!