From three old PC's I have assembled myself a new under purchase of a Asus motherboards and a powerful processor fan. (Windows 8.1 32 bit, ATI Radeon HD 5450, 3GB of RAM, Intel Core2 6300 @ 1,86Ghz, 1 internal and 2 external hard drives) After some time tended the PC crashes. My guess is that the power supply fails, proved to be correct. With the significantly stronger Seasonic power supply of PC is running properly.