MONITERS

The most obvious cause for this would be the video card that may have gone bad,also you may want to check for updated drivers
Check the memory slots to make sure they are inserted in slots securely
Install another video card and see if this will clear up the problem

First, Re-seat the video card, and the monitor cable.

The next 2 posabilities are:

1. The monitor is bad.
If you have no video at all, not even during the POST at startup, this is a posability.
The simplest way to check is to try a different monitor, or connect this monitor to another computer.

2. The video card is set to a refresh rate that your monitor does not support.
If you have video during the POST, this is the likely cause.
Boot into safe mode, and set the display settings to 16 color 640*480 mode.
You should have video after you re-boot.
Update the MB chipset drivers, and then the video card driver.

That should take care of the problem.

i fyou set resolution/frequency above what monitor can handle most will shut down. try sfe mode and see if that works, if not reseat video card. then check self test on monitor, then replace either monitor video card or both

good luck