My computer stops working. Urgent Help!!

[Tubbychubby]

This is totally weird. My computer is working fine today until I decided to add 2 more gig of ram into it. After that, it won't even boot up, there is no beeping sound, and there is no signal to the computer monitor at all. The screen is totally dark, displaying "no signal". After I remove the extra RAM, and switch back to the original working configuration, the computer still won't start up at all. I checked all the cable, video card cables, unplug and re-plug in everything. Still, it doesn't help at all. The power supply is working, since all the fans are still working. I stripped the computer down to the bare essential, one strip of ram, one HD, video card.. still, the computer won't boot... does that mean my motherboard is fried?
I tried to clear CMOS, but it seems to make it worse, now the computer will start for 2 seconds before restart itself again.. and keep repeating doing that until I shut it off.
For some weird reason, my computer case don't have a built-in speaker (case: Raidmax Sagitta), there is no cable that I can attach to the speaker pin on the motherboard. But I notice something, after I remove everything (including cpu), I was able to power up the computer without it restarting every 2 seconds. But the screen is still totally dark (after I put the video card in to check).. but once I put CPU back into the motherboard (without the video card) the computer will keep restart itself again..what can i do now?
My computer setup is as follows:
Core 2duo 6420
OCZ 2P800R22GK: 2 Gb (the extra 2Gb of RAM that I tried to install today is exactly the same as the original one I had inside the computer before this incident
Motherboard: Gigabyte 965P S3

 

[guitto]

When you clear the CMOS, there should also be a pin with 3 male connectors and a 2 pin female connector. Place the female connecter on the other 2 pins after you have taken the battery out. This should resolve the problem, also you may have overheated coincidentally.

 

[Tubbychubby]

When you clear the CMOS, there should also be a pin with 3 male connectors and a 2 pin female connector. Place the female connecter on the other 2 pins after you have taken the battery out. This should resolve the problem, also you may have overheated coincidentally.

done that, but it didn't help. Can it be the PSU? the thing I don't understand is that if it is due to PSU, why does the fan still works?

 

[raybay]

There are three power rails on the power supply. One going out while the other two are good could cause the problem in certain cases. You can test with a power supply tester from Frys, CompUSA, or other computer parts store for about $10, or you can just try a borrowed power supply from another computer.

 

[you use a 286]

in the past this has happened to computers i was fixing, when i put new RAM in, it wstopped working. try the old RAM again and see if your computer works

 

[Tubbychubby]

somehow my computer came back life, i thought the PSU was toasted so I bought a new one. With my old ram in place, I was able to boot up my computer. As I thouhgt I have fixed the problem, I placed the new RAM in the Channel one again.. same thing happened once again. Computer failed to boot up, with no signal to the monitor, and it didn't help with the removal of new ram either. I then took out everything, insert the new ram into Channel 0 this time, with nothing in channel 1, using the OLD power supply, the computer boot up fine, strangely, after replacing the new ram with my old one into channel 0, the computer stops working again. To make long story short, I finally got the computer boot up again with my old set of ram, since I Got tired of trying to insert the new ram and having my computer died on me. I decided to stop it. I asked the OCZ rep, they told me to leave the old ram in place, go to bios, set voltage to 2.1V DDR800 and make sure 2T is listed, reboot, power off and insert the new ram in, then see if the computer will boot up. Here is my question, since I never OC my system (hence I never play around with the BIOS).. where can I go in BIOS to change it? (in MIT .even with ctrl+F1...I couldn't even find the place where I can change the voltage of ram to 2.1V, unless they go by some other technical term, and the place I can check whether 2T is selected)