Hi, I just bought a Corsair 850HX to replace the Corsair 750hx I had previously had in my computer. However, since the installation, my computer randomly shuts down, almost as if power has been abruptly cut off to it. However, right after the fans stop spinning, the PC boots back up again. Could my power supply be the cause, considering how it started only after I installed the new PSU?
The obvious thing to do is to put the old PSU back in and see if you can repeat the problem.
If the system runs reliably with the old PSU, there is clearly something wrong with the new one.
If you have the same problem with the old PSU, you have something else wrong.
Here is what I think is happening:
A PSU has a circuit that monitors the three main output voltages: 3.3, 5, and 12 volts. When you turn on the computer, the PSU takes a fraction of a second to stabilize. After it does, the PSU sends a control signal called something like "PowerOK" (pin 8, grey wire) to the motherboard. The CPU needs this signal to boot.
System boots, and you are up and running. You load a game or a program that puts a very heavy load on one of the outputs (generally the 12 volts). It drops out of tolerance. You loose the PowerOK signal. That forces a hardware reset. And the system reboots, giving a seemingly random shutdown.
I had a no-brand(XION or something) 700w psu that I stress-tested and destroyed. It was no match for the power draw from my computer. I then upgraded to a Corsair 750HX, which I bought for $140. however, about two weeks after I bought it, I saw a deal for the 850HX for $120, so I RMA'd the 750HX and bought the 850HX, which brings us up to current speed. I am considering just getting an RMA for the 850HX, is that probably the best bet, seeing as this never happened with the previous power supply