Computer (Hard) Freezes During Games

[sw4ve]

The Problem(s): 

1. I am currently experiencing an issue where my computer freezes and becomes unresponsive while playing games.  This can happen after 20 minutes or 5 hours, there does not seem to be a pattern.  I also get a buzzing sound through my headphones that changes frequency after my PC freezes.  I used to have an old (15+ years) monitor hooked up to onboard graphics that would quickly flash through solid colors when my computer froze.  
2. I get occasional hangs right after entering my pin as I log on to windows
3. My HDD sometimes does not show up in Windows explorer, device manager, etc. or may disappear while I am using the computer.  My OS is on my SSD 

 

Specs: 

Windows 10 Home 64bit

2x8GB DDR3 1600 RAM

Gigabyte Z97X-Gaming 3 (BIOS version F4)

Intel Core i7 4790K

Nvidia GTX 780

Samsung 850 EVO 500GB SATA SSD

5TB Western Digital Black HD

EVGA 650 Watt PSU

Sound Blaster Z Sound Card

 

Troubleshooting:

So far I have cleaned my case, fans, and radiator.  I stopped using my 2nd monitor (that was connected to onboard graphics).  I tested both of my drives and they both passed the short SMART test.  I visually inspected my motherboard for blown capacitors or burned out chips/traces.  I disconnected and reconnected my HDD to make sure I had a good connection.  I also looked for any loose wires (and didn't find any).  I stopped using my sound card and removed it from my motherboard (until I got crashed with it disconnected, then it was installed again).  I ran the Intel processor diagnostic tool and my processor passed.  I plugged my PC directly into the wall instead of through a power strip.  I also tried the latest Nvidia drivers and drivers from a year ago (before I had this problem) but neither of those resolved the problem.  I have also done a clean install of windows and the problem persisted after the reset.

 

Any advice or suggestions would be much appreciated.  Thanks!