I just got Watch Dogs 2 for PC yesterday but when i start the game after 5-10 minutes it crashes.
First off you should upgrade your RAM. 8GB used to be more than enough for gaming. 2016 thoroughly changed that. I suggest at least 12GB. 16GB is recommended.
After that I suggest the Rx 470. I am not an AMD fanboy. I use and enjoy an Intel/Nvidia pilot and copilot rig.
http://postimg.org/image/gnemua29f/ Yes, my monitor is a dinosaur. My 1080p 32" TV dies this week. Need to save up for a loooong time before I can replace it.
Maybe the computer is all right but some maintenance needs to be done–like cleaning the cooling system, whatever it is.
What resource is it running out of? Network? CPU? memory? Disk space? graphics capability?
A better computer