PC wont boot- no video output

[dongs]

We have an Aspire T310 desktop with a P4 CPU

When I power on, the fan revs up to max and the HD LED flickers but the machine does not provide a video signal and from the sound of the HD, Windows is not booting. There are no HW beeps signalling an error.

I swapped out the power supply and tried both the HD and the memory in another machine. All are fine. I also reset the CMOS memory using JUMPER JP1. I also tried booting without the HD and CD connected to the motherboard but the Acer logo does not appear on the LCD screen which works fine on another machine.

I guess there must be a problem with the CMOS (corrupted), the motherboard or the P4. Can you help me narrow down the problem without swapping out the P4? Is there a test point I can use to identify the problem?

Many thanks

Checks:
no splash screen, no BIOS screen, no beeps
Fans- both, rear spining fast
LEDS- power on, flashes twice
HD and CD-ROM LEDs flash, CD drive can be opened
Reseat- reinserted memory
Changed PSU
Reset CMOS memory (jumper JP1)

 

[Triple6]

Its rarely the CPU, but there's no way to test the board or CPU without swapping in another CPU or testing the CPU somewhere else.

Have you also disconnected al headers such as the audio and USB ports and card reader that are connected inside. Also disconnect all devices connected externally except the monitor. You can even disconnect the front panel LED's and switches and use a screw driver to short the two power switch pins on the motherboard to turn the computer on in case it's a broken switch.