Are my parts dying?

[GrayFalco]

Hi LTT Forums, my computer randomly shut down and rebooted when i woke up, and then shut itself down again after a few minutes. Went into the bios and then found out that it froze in the bios so I cleared CMOS and reset my overclock and it shut itself down again and rebooted another time and now it seems to run fine again. Here's the thing, it happened sometime about 2 weeks ago as well except it didn't reboot when i shut it down, after power cycling a few times i managed to turn it on only to see a failed overclock message, ok so I reset my overclock of 4.2ghz at the time, went into windows checked my temps and they hover around 38c, then it proceeded to shut down again, I cleared cmos and it seemed to be working fine for the whole 2 weeks, temps on load were fine and all.So 2 days ago, i thought it was stable enough to give it another overclock so i updated BIOS and stuff and gave it a mild OC of 4.0ghz at 1.245v but apparently that didn't seem stable as it crashed but without BSOD and temps being cool.Ran memtest and it doesn't show any problems. Anyone got a solution for this?
The motherboard and power supply are less than a year old

Only thing that's clearly faulty is my exhaust fan in which im going to buy a new one in a few hours

PC specs:
PU:Intel i5 4670k
GPU:Gigabyte Geforce GTX 970 G1 Gaming 
MOBO:Asus ROG Maximus VII Hero 
RAM:G.Skill Ripjaws X 8GB 
SSD:Sandisk Ultra Plus 128GB/Crucial M500 120GB 
HDD: 1xWD 1TB Caviar Black 
Cooler:Noctua NH-D14 
PSU:Corsair HX850i

[fisch1l]

Overclock made it unstable. Check the drivers!

[GrayFalco]

Nothing seemed wrong with the drivers, the overclock of 4.2ghz ran for a year or so. I noticed that the PC dies if the exhaust fan stops working, is that any way relatable?

[fisch1l]

Yes that is relateable it could be linked to temps. (Aka, overheating?)