"wouldn't work" is not the same as "10 minutes". You have a fine heat clue so time to redo all your heatsink work and make sure all fans work like new.
So for 2 months ago i was at my friends house with my pc but after 10 minutes of being started it began to lag so i couldnt even open google chrome (it was suddenly super laggy)
So when i got home my brother tried to fix it and he did, but recently i was at my friends house again with my pc, and it wouldnt work. And i really do not understand why. And my brother cant remember how he fixed it. And i do not think it has anything to do with the Cpu or the Gpu nor the hdd. But i dont know is it possible a cable in the pc could be loose?. My gpu is a gtx 960 turboclocked with 4 gb and my cpu is a I5 6600k 2.4ghz. I remember sligthly that my brother told me that he switched out a cable and suddenly it worked but neither me or him can remember what we did. Please help and thanks. Have a great day