On the BSOD there is often an error code that can be looked up to give you a better idea of exactly what the problem is and sometimes even how to fix it. Random kernel errors indicate something reported something the system didn’t like and it spazzed out. If my understanding is correct, 8.1 still uses a version of the NT kernel and it sometimes fails when run in 64 bit mode. More likely is a memory glitch. Try removing, cleaning and re-installing your memory. Failing that, reinstalling the OS or taking this as a signal to upgrade to W10 are the nuclear options. Bear in mind, I retired from IT support 13 years ago so there may be more up to date folks on here.