Right, your first 2 crashes have indicated a fatal hardware error has occured. The 0x124 WHEA_UNCORRECTABLE_ERROR is a generic error so the crash dumps conatin very little preactical information. Your 3rd crash however points to your processor not generating any interrupts. The processor became unresponsive so windows crashed. It does say the driver responsible was nvlddmkm.sys which is an Nvidia system file. I would run prime95 but I would not let temperatures exceed 65 degrees Celsius as anything higher can damage AMD cpus. I would run it for 6-12 hours personally. but keep monitoring it every now and then as you don't want to overheat your CPU.
Okay, so the hardware error, does that mean a component is broken and unfixable (has to be changed)?
I'm gonna give Prime95 a shot, and see how it goes, thanks.