Computer Force Shut off Slow run time

[deskace]

Hey guys,

Last week was when this first presented.

While playing a game my PC force shut off (and then rebooted itself). When reloading the game it shut it self off a few minutes in. I ended up opening up my computer and cleaning it out. I attributed this to having cats increasing my need to clean the computer and it worked fine for about 7-10 days.

Today, it presented with the same issue. But upon rebooting, it was going astronomically slow. I attempted to shut it off and it took me well over 20 minutes to be able to open the windows menu and click shut off and it to fully shut down (it is currently stuck on 'Shutting down'.

I am unsure of what would be causing this problem. However I have a few ideas.

1: It is likely not that the power where I am is inconsistent as I have it hooked up to a UPS (because the power where I am is very inconsistent)

2: It might be overheating. This would explain why cleaning it out temporarily solved the problem. I don't know why it is overheating now. One thing that this led me to question is if the thermal paste gave out. The cpu cooler was not hot on the most recent shutdown. I have not reinstalled thermal paste since the initial build

3: It might be a PSU failure. I am hoping it is not this and am unsure of how to test if this is the issue or deal with this issue if it is the case.

4: It might be the encrypted hard drive is the issue. I have had it encrypted for about a year. Unecrypted it last week when the first issue arose and reencrypted it yesterday. If this is the problem, I am not sure why or how to solve it.

5: It might be a combination of the above with causing hardware failure.

If you have any advice on how to proceed with testing or on what a likely cause is that would be much appreciated. Thank you very much for your time

For Specs, let me see if I can find a list.

CPU: Intel - Core i7-4790K 4.0GHz Quad-Core Processor

CPU Cooler: Cooler Master - Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler

MoBo: MSI z97's sli krait

PSU: CORSAIR HX Series HX850 850W ATX12V 2.3 / EPS12V 2.91 SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular ...

RAM: Team - Dark 16GB (2 x 8GB) DDR3-1600 Memory

Storage: Corsair Force LS Series 2.5" 240GB SATA III MLC Internal Solid State Drive (SSD) CSSD-F240GBLS
Seagate Desktop HDD ST2000DM001 2TB 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard

Thermal paste: ARCTIC MX-2 (4g) Carbon-Based Thermal Compound, Non-Electricity Conductive, Non-Capacitive

GPU: MSI - GeForce GTX 970 4GB ACX 2.0 Video Card

Case: Cooler Master - Elite 431 Plus (Black) ATX Mid Tower Case

 

[deskace]

Update: I unencrypted my harddrive and my computer speed is back to normal.

I then attempted to use computer again and it force shut off as it has in past. Upon rebooting it I am running prime95 and carefully watching temperatures. They have yet to go super high.

Thermal paste should arrive tomorrow and when it does I'll reapply to heatsink. But I am somewhat doubtful as to what my cause is.

It doesn't seem like overheating as I can't seem to force it to overheat.

It doesn't seem like PSU failure based on how I have read about it (slowing down, laggy)

I am very unsure of how to proceed from here

 

[deskace]

Update:

Fully took computer apart, cleaned every piece and reapplied thermal paste and no success. The problem persists.

Does anyone have any advice on what I can try? Please