Can't wake PC from sleep.

When I attempt to wake my PC from sleep using my keyboard, the PC lights up for just a second, but then shuts down and has to be restarted (which occasionally causes a static noise within the PC). It may be a hardware defect, but it can't be the GPU or RAM, as removing the GPU and replacing the RAM does not solve the issue.

Trying to wake my PC from sleep using any other method simply restarts the PC.

Does anyone know what's causing this? Or what part to replace?