Two days ago, my PC just switched off with no warning. So I thought I switched off the power by accident. Pressed the power button and one of my cooling fan light turns on then off for a split second then nothing still happens. So I opened up my PC and pushed all connections in just in case one of them is loose causing a short circuit. Pressed the power button. This nothing at all happens. So the first component I wanted to rule out was the GPU -  since it was the easiest one to remove. Pressed the power button. Nothing happened. So, I ruled out the GPU. I REPEATED this process for my RAM, DVD Drive and HDD. I still get the same problem. So lastly, I switched the power supply (hoping the motherboard and CPU is fine). I get the same result. So now I'm left with either the CPU and motherboard. I hope it isn't the motherboard...
It appears that you have chosen a good route to start at with the Power Supply Unit . However another easy test is to determine if all your RAM is working properly. Assuming you have more than one RAM module remove all but one and test for a change in performance. Also try the modules in different slots. Don't stop this process until you have checked all modules and hopefully one will be apparent as FAULTY. I take it to mean from your statement "I repeated this process for my RAM," that you only VERIFIED that it was "seated" tightly. It may be possible also that if a sensor is detecting a non functioning fan that it shuts down immediately as well. truenorthI don't know if this is important but, right now, the only thing I have in my computer is the power supply, CPU and the motherboard. Tested that. Nothing happens. I will try the RAM slots. None of the cooling fans are connected. The only one connected is the CPU one. Quote from: StealthRogue on December 05, 2010, 01:47:49 PM

I don't know if this is important but, right now, the only thing I have in my computer is the power supply, CPU and the motherboard. Tested that. Nothing happens. I will try the RAM slots. None of the cooling fans are connected. The only one connected is the CPU one.

Is it doing shutdowns in this configuration ? ?