That samsung 850 EVO could easily be the problem here. I’ve also got a 850 PRO model and when i enable pagefile on that drive it will BSOD the system, especially when i run Unreal Engine. Just disable the pagefile on drive C and manually enable it on your HDD instead. Worth a try! (Since i disabled, i get no more BSODs, but SMART still showing degradation of the drive. Thanks samsung.)
PSU is loosing power over time, i think thermaltake was mentioned an average of 10-15% of loss per year, since the capacitors wears out. It’s age could be a fault if it’s an older model. 7 years of warranty won’t guarantee the 100% performance, you would likely end up getting out a 400-500W at tops after a while.
You’re lucky to got 2 RAM stick, take one out and test the game. Maybe one of them is faulty.