Use Who Crashed (the free version is fine) to determine what's causing the blue screen.

@ejn63​ what is who crashed please is it an app 

https://www.resplendence.com/whocrashed

@ejn63​ my engineer says it heat that causing it and that I use clean the PC and add thermal paste and he said I should pay 15,000 naira for both service is that true because I noticed it always crash once I am doing a heavy task like watching anime with high quality and opening multiple browser tab and it doesn't lag that the funniest part it just show PC run into an run need to restart and everytime it shows it always different error code I did hardware diagnosis but itsays the hardware is ok

The system is 15 years old and if it hasn't had internal cleaning and thermal pad replacement, that may help.  

That said, if you're using the system for intensive work, a new(er) system would be a good idea -- on its best day, this system is too old to handle a contemporary workload.

@ejn63​ okay but I already take the PC to my engineer I'm waiting to collect the PC I hope it works