If you say your whole pc crashes.. there must be a problem with your pc. Unstable ram for example. The next thing you'll answere is, it's fine with other games. This train of thought is wrong, because not every game and every program puts the same load on ram/cpu/gpu.
You're using a 5700 xt - what i had befor, too - and i know that this graficcard can cause a lot of problems. Sent mine back, had blackscreens and crashes as well. Probably here is the issue. It's hard on this point to help you.. do you have a friend whose graphics card you could borrow to test? the best would of course be a graphics card from nvidia, not from amd again.
What u also can do, is to test your whole system for stability with programs like prime 95, kombustor/furmark, memtest etc. pp.
