Recently purchased a new ASUS P4S800D MB to be installed in a new case with new power supply. The problem I have is I get no response from my monitor. I have tried 2 CPU's(1 brand new) and 2 video cards(1 brand new) and have had no difference in the response. The LED light on the MB comes on and so do the cooling fans. I any one has any ideas on troubleshooting this problem I would appreciate the help. Thanks.

You could exclude the monitor as the problem if it works on a known good box.

If the LED and fans are working, then the mobo is at least operating at a basic level. Try taking the mobo out of the case and putting it on a piece of cardboard. See if it will boot up that way. If so, then the new case and mobo have a short somewhere that you need to find.

If not, try a different PSU. If still no response, RMA the mobo.

If the monitor works on another system and placing the MB on a piece of cardboard does not help, then check the MB for any visual signs of defective parts, i.e., bluging, leaking, or ruptured capacitors, and also check the CPU for cracks or chips.

If they look ok, then resetting CMOS with a MB jumper(see MB instructions), or removing the CMOS battery for at least an hour sometimes fixes things.

Also, check that the CMOS battery has a 3 volt charge, and is making good contact in the MB insert.

If no luck, then see if you can get a display with just the PSU, MB, CPU, RAM, video card, and monitor connected.

If no good, then reseat the RAM, try it in different slots, or try different RAM.

If still no luck, then it may be time for a new CPU, or a new MB or PSU(as suggested by saphalline).