Parity checks are the simplest form of error detection code and are techniques that enable reliable delivery of digital data over unreliable communication channels.
A Parity error can occur from many sources including faulty HDD,MB,GPU,Raid setup or Memory module.

From what we know so far from your description your system has been running OK then suddenly you get a BSOD. Are you able to get into your OS via Safe Mode and are all your drivers up to date?

What we need to do is establish exactly where and when the error is occurring and for that we need more information, so lets start.

What HDD or SSD are you using?.
What OS?
Your PSU?
Have you obtained any logs, mini dumps etc?.
What cools your system CPU?
Have you tested your DIMMs with Memtest86. ?

Testing you DIMMs and GPU on another machine will not necessarily determine that a parity error should not occur on your machine and it could be related to a failing PSU, MB component or settings in your Bios, When did you last update or make changes in your Bios?

Can't think of anything else at the moment but when you report back other ROGers will come on I'm sure, with more questions and suggestions to determine your exact problem.