PC Crashes

[Kanpai]

I've got an Acer Aspire AX1301 that's been rebooting itself now and then whenever I try to watch any video content on there; aside from this it will run for hours and hours with no problems.

At first I thought it might be the onboard graphics card so I decided to purchase an ATI 5450 to replace it, but to my luck the pc just rebooted itself again.

Does anyone have any idea what else it could be? Note it's only happening when video content is being played.

Thanks in advance

 

[trickynickyuk]

Could be memory run memtest see if you get any errors could also be an overheating problem make sure heat sink and fan on cpu are clean