BleepingComputer.com: intermittent blank screen - motherboard problem? graphics card seems fine

hi everyone

have got a Compaq Presario Media Center SR2019UK Desktop PC with a display fault.

99% of the time, when powering up there will be no display and the monitor stays in standby mode, yet if i unplug the vga cable it will detect that the cables been unplugged and alert me so it obviously recognises a connection but just no display. there is the odd 1% of the time it will work but usually after the next reboot it will not work again.

i have tried a different monitor and cable only to get the same result so that eliminates them. the motherboard has onboard graphics so i have tried a new pci-e graphics card in it and still get the same result so it does'nt look like its the onboard graphics.

i then tried running the diagnostic software microscope by micro2000 (when i could get a display!) and no faults come up when running the display tests.

i also tried the post-probe diagnostic card in the motherboard and it comes up with many different codes (often different sets of ones from time to time) of which i would not expect given the amount of them.

has anyone else ever experienced a similar problem or may also think the fault lies within the motherboard?

thanks