Hello, my pc won't boot at all, not even the PSU fan would run, so I thought I had to replace the PSU, since it was a fixed one. I bought a new PSU, installed it, connected only the 20pin and 4pin cpu connectors, pushed the power button, and the pc wouldn't boot at all, not even the PSU fan.
Next, I unplugged the 4pin CPU connector, and pushed the power button, and the PSU's and CPU's fans started running. I turned the PC off, plugged the 4pin connector, just in case, turned on the PC, and the fans wouldn't run again. However, I noticed that, right after I pushed the power button, the CPU would make a noise and even moved an instant.
Then, guessing the PSU was not the problem, I installed the old PSU, the one I first thought was the culprit, and, again, connected only the 20pin and 4pin connectors. The fans wouldn't run, but the CPU fan would make the noise and slight movement again. I unplugged the 4pin CPU connector, pushed the power button, and the fans would run, which makes me thing the problem might have to do with the MoBo or processor. I wish I were wrong.
I decided to take out the CPU heat sink, just in case, and noticed that one of the clips that connect the MoBo with the CPU fan was broken, and the fan was a little loose. I even found the rests of the broken clip, which makes think that it recently broke. I removed the heat sink and found the processor covered with a white solid mass. I'm not sure if it is thermal paste, and I don't remember if I had removed the heat sink before.
I'm thinking that the CPU might have overheated; however, I have read that when it happens, at least the PSU would work, and its fan spins, but I don't understand why my two PSU's fans not even run. Would someone explain that to me?
Also, should I consider the CPU is dead, or is there a chance something else is the problem? Should I fear the Mobo is also damaged? I hope not, since the CPU fan spins when the MoBo is powered with the 20pin connector.
Electrical connections do wear out over long periods of time.
Unless you plug/unplug them on a frequent basis to the point that you eventually wear out their tin/gold/whatever plating, most well-designed same-to-same metal connections in a relatively benign environment (ex.: PC in a home/office) will last for decades. Good soldering jobs should also easily last several decades.
I'm thinking along the lines of repeated thermal expansion/contraction.
Most components either have reasonably close expansion coefficients or enough flex to avoid stressing solder and mechanical joints. Old systems should actually be LEAST vulnerable to this since their weaker or nonexistent power management significantly lowers the frequency and magnitude of temperature changes while in modern CPUs, individual CPU cores can go from 30C to 50+C within seconds multiple times per minute.
One common killer/disruptor for old electronics is "tin whiskers" where conductive dust builds up on solder joints and eventually cause shorts. Those bridges are too weak to carry harmful amounts themselves but if they mess up a voltage regulator's feedback loop, they can cause the VRM to destroy its load. I have personally seen electronics fail to work due to conductive dust buildup and come back to life after something as simple as a thorough cleanup a handful of times.
Hi. To finish the thread, I took the PC to a repair-shop, and they told me the MB was damaged and said they may fix it. After some days, they said the MB had no solution and offered me a used one. They replaced the MB, with the same microprocessor, and it is working fine, now.