No Signal Screen on PC

[crymetyme2]

Recently I was using my old PC and I was just turning on a new tab in google Chrome in Windows 7
Suddenly My computer shutdown ,my all wire and electricity is alright.
When I turn on the PC it Just shows the NO SIGNAL Screen. I removed my ATI 9250 graphic card and used on board graphics but still no signal , I am pretty sure it is not the screen problem cus my keyboards three lights blinks once and then the Num Lock LED doesn't light by defult even If try to press the Num Lock key , the NUMLOCK , Caps Lock or Scroll Lock doesn't light up.
I have tried to remove some rams and tried to use single rams one by one but it still doesn't work.
I think that the boot menu is crashed but I am not sure what is the real problem with my pc.
And yeah the power supply is still working.
If any one else have this problem before , please help out 😀

Dell Optiplex GX270
Pantium 4
756mb ram
40 GB Hard Disk
ATI 9250
550 Power Supply

 

[C12Friedman]

My first inclination here would be replacement of the CMOS battery (little watch battery on the motherboard) - see where that gets you...
Also, check to ensure your connections are seated firmly

 

[hang-the-9]

Nothing to do with the boot menu, if you get nothing on the screen, it's not even getting far enough to try to boot.

In a P4 system of that era, check the motherboard for issues with the capacitors if any of them are puffy or broken open. They should be flat and shiny on top, no gunk on top of them. Could be the power supply also, but it's probably the motherboard.