What kind of a crash is it? Does it exit and go to desktop? Does it freeze the whole system? Does the screen go blank? Any error messages?
Id suggest you run on-screen display ( msi AB has it) and keep and eye on temps, voltage, etc etc while the heaven is running,
Unistalling and reinstalling drivers, heaven, dx11 is also a good thing to try.
Are you overclocking your cpu by any chance? If so, run everything stock and try the bench again