[Annolyze]

So I have been recently trying to fix the issue with my mothers computer. Its an older PC.
Inside it has a socket 775 mainboard with an Intel core 2 duo CPU and onboard video.

The problem is when powered it displays no post screen. So entering the BIOS is not an option.

Things I've tried in my troubleshooting efforts are as follows.
I've swapped the monitors with a known working unit. Problem unsolved.
I tried to instal a new video card problem not solved.
I replaced the psu with a known working unit. No cookie.
I cleaned the contacts on the ram sticks with an eraser and tried reseating them 8 times to ensure proper contact in the slot. Not fixed.
I replaced the cmos battery. Not fixed.
I installed a new motherboard. Not fixed.
I installed new ram. Not fixed.
I tried a new VGA cable. And a new DVI cable didn't solve it.

I have run out of ideas and am at my wits end. I would love a fresh point of view from someone. Thanks

 

[JimE]

What kind of indications are you getting that it is working or not working?

You will need to pull it apart and test. There is a guide here> http://www.techsupportforum.com/forums/f255/how-to-bench-test-troubleshoot-your-system-171424.html

 

[Annolyze]

The computer starts up fine as it seems. But there are no keyboard lights or any indication the keyboard is working. And it does not display anything on the screen. No post screen. The CPU fan runs and the hard drive sounds to be running. Today I tried a new CPU with fresh thermal paste. Still did not fix it. It seems unable to provide display. As I said before I have tested the monitor with another computer and tried a different known working monitor. Today I also tried a new higher wattage power supply. Mystery stands unsolved.

 

[JimE]

Likely a motherboard issue. As it POSTs, you should get power to the keyboard. So it's not POSTing.

POST = Power On Self Test

Which is the hardware test which occurs before it tries to boot (ie: load the OS).