Can you give some more information about your power supply, eg. Make and model. Not all power supplies are created equal, and there are a lot of cheap low quality units out there that say they can deliver X number of watts, when in actuality they can only deliver half their stated wattage over a sustained period. There are also a lot of PSUs that have severe voltage ripple issues which can lead to shutdowns as well, largely due to being made with low quality capacitors.
Other things to check for include temperatures, you can use programs like HWMonitor to look at those. If your PC is overheating, it will start throttling back performance to protect itself from damage and may also trigger a shutdown if throttling is proving to be insufficient to get the temperatures back down to a safe level. If your CPU or GPU are exceeding 95 degrees celsius, you have an overheating problem.
Bad RAM can cause this problem too, though often memory errors will result in bluescreens and other errors, it doesn't hurt to run Memtest to make sure you don't have a bad stick that could be causing problems.
This could also be a sign of a failing motherboard, particularly if it's fairly old. One thing to check for is look on your motherboard and check the capacitors on it. If the tops of the capacitors are bulging or are actually leaking, then your motherboard is definitely on its way out.
Other things to check for include temperatures, you can use programs like HWMonitor to look at those. If your PC is overheating, it will start throttling back performance to protect itself from damage and may also trigger a shutdown if throttling is proving to be insufficient to get the temperatures back down to a safe level. If your CPU or GPU are exceeding 95 degrees celsius, you have an overheating problem.
Bad RAM can cause this problem too, though often memory errors will result in bluescreens and other errors, it doesn't hurt to run Memtest to make sure you don't have a bad stick that could be causing problems.
This could also be a sign of a failing motherboard, particularly if it's fairly old. One thing to check for is look on your motherboard and check the capacitors on it. If the tops of the capacitors are bulging or are actually leaking, then your motherboard is definitely on its way out.