Originally Posted by Hightower
I guess you could start it in safe mode and see what happens, as the computer boots up you'll have to hit one key to take you in to an options page. Usually delete, esc or F1 key should do it. At least you'll be able to see if the screen remains on for a period of time. I'm sure someone more experience with such things will come along later and help you.
If I understood then he's not getting any display on the monitor so booting in safe mode will not help.
Originally Posted by C2ribs
I switch the main power on and it appears to be firing up and the screen is switched on at the same time comes up with a blue light but then the screen does not start and shows "no signal" in words before switching down into the sleep mode and then nothing happens.(all happens very quickly) The main computer remains on and the keyboard appears also not to generate any response. The only way to switch of then is pullng the mains plug out
If I have understood you right then you are seeing the same as the monitor would display if you turned it on with no PC connected? And you never see the "Power On Self Test" Screen - which is the black screen usually with a logo in the top right and then various bits of "technobabble" in white text. At that point you can normally press F2 or DEL or some other key to go into the Bios settings...
If you are not getting this far then there are a few possibilities:
(1) The PC is not putting out any data on the graphics adapter
(2) The data is not getting to the monitor
(3) The monitor is not working correctly.
I'd rule out 2 and 3 either by trying that cable and monitor on a different PC (e.g. laptop?) or swapping with a spare monitor and cable if you have them (e.g. from the office or many modern TV's have a VGA-in option).
Assuming they are working fine, then it looks like option 1. If it is a relatively ordinary computer (not a specialist games or video editing machine) that is reasonably modern then it probably has the video output integrated onto the motherboard. The fault could be the power supply, the motherboard itself or the processor (and possibly even faulty or loose memory) - any of which could produce the symptoms you describe. Other than checking that nothing has come loose inside or obviously burnt out there is not a lot you can do without knowing what you are doing or swapping parts around. Its worth doing a quick google on the fault and make / model of your PC - a few years ago half our office PC's starting developing a very similar problem and it was a known fault on the Dell Motherboard which dell were swapping, on site, free of charge despite being out of warranty.