If you have its motherboard manual, try to check its beep code. This will give you some clue on what is the fault.
Usually this could be dirty contact of RAM and video card. Try to clean its contact or you can try to reseat it first. If that not fix it clean it with clean soft eraser, its edge contact connector. But do this with your unit completely power off and unplugged from wall socket and UPS if you have.
Or some shorted component. Try to check it one by one to find the fault.
Answers & Comments
If you have its motherboard manual, try to check its beep code. This will give you some clue on what is the fault.
Usually this could be dirty contact of RAM and video card. Try to clean its contact or you can try to reseat it first. If that not fix it clean it with clean soft eraser, its edge contact connector. But do this with your unit completely power off and unplugged from wall socket and UPS if you have.
Or some shorted component. Try to check it one by one to find the fault.
Post comment if this doesn't fix it.