When you turned on your desktop then monitor says no display or no signal massages. Follow the undermentioned instruction for the troubleshoot.
First you check the monitor and VGA cable with a another computer. If the error massages displayed replace the faulty VGA cable or Monitor.
Open the CPU cover
If you have a Graphic Card remove it clean gold pins and reinsert then try
Remove the Graphic Card and clear the CMOS then try with on board VGA
Clear the CMOS and check the CMOS battery has any damages.
Remove RAM cards and clean the gold pins with an eraser. then plug them and power on the computer. If you have more than one RAM card insert them one by one and boot the computer. If you have only one RAM card then try to boot the computer with an another working RAM from outside computer.
Unplug the power supply unit then connect it to the AC and make sure your psu provides the correct 12V and 5V. You can check this by a power supply teset
Remove all attached HDD's and Optical drivers then clear the CMOS and then try to boot.
Remove the processor and try with a another same working processor (Processor burnt is rarely incident)
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