All of the BSODS are indicating a critical process died. It's highly likely this is due to a faulty memory module. You'll want to test your RAM with memtest86 for at least 10 passes or until you hit errors. If you find errors you'll want to shutdown pull all the memory except one module. Retest for 10 passes or until errors. Repeat until you've identified all bad sticks and replace them.
A critical system process died
Arg1: ffffc281f3ca5800, Process object or thread object
Arg2: 0000000000000000, If this is 0, a process died. If this is 1, a thread died.