Hi Rarnwi and welcome to TSF !
What's the exact model of the emachine and the complete system specs (video card, number and type of drives, additional pci cards, ...) ? What's the brand, model and wattage of the power supply (look on the sticker on the side of the power supply box) ?
Enter the BIOS at startup (look for some "press xx to enter setup" message) and see if there's some hardware monitor screen or pc health status screen. If so report your temps, fan speeds and voltages. Since it's an Emachine it's possible there's no such screen.
Make sure all the fans are spinning properly and aren't clogged by dust, check the CPU, video card and power supply.
A computer shutting down after some time when playing or watching videos usually points to overheating (either the CPU or the video card) or a failing/underpowered power supply. See if you can borrow a friend's power supply to try your computer with.
What's the exact model of the emachine and the complete system specs (video card, number and type of drives, additional pci cards, ...) ? What's the brand, model and wattage of the power supply (look on the sticker on the side of the power supply box) ?
Enter the BIOS at startup (look for some "press xx to enter setup" message) and see if there's some hardware monitor screen or pc health status screen. If so report your temps, fan speeds and voltages. Since it's an Emachine it's possible there's no such screen.
Make sure all the fans are spinning properly and aren't clogged by dust, check the CPU, video card and power supply.
A computer shutting down after some time when playing or watching videos usually points to overheating (either the CPU or the video card) or a failing/underpowered power supply. See if you can borrow a friend's power supply to try your computer with.