i5-2500K Crashing

[chrispycrunch]

For years, my system was stable but in the last month it crashes under specific cases of general usage (no gaming, just surfing on web and MS office). I have an i-5 2500K overclocked to 105x 4 (4.2Ghz). O/C never had a problem until now.
1) I opened chrome + website that loaded a 360 view of a car on nissan.ca
2) foobar playing music.

Computer crashed and froze. How should I diagnose the problem? If it still crashes after returning to stock speed how do I troubleshoot?
Also: Crashed under Windows 10 and 2) updated to creators update and still random crashes.
I also ran a crystalmark benchmark. When it got to the graphics card (which is integrated) testing, the computer froze.

 

[Noghri2]

My first things I would do, aside from returning to base clock speeds, is see if Windows is generating a Windows Crash dump file or check Event Viewer to see if anything is logged for crash or freeze.
Look at motherboard and see if any capacitors are bulging or leaking.
If not, then installing software to monitor CPU temperatures.
Clean CPU fan and heatsink with compressed air. While cleaning those, might as well blow out any dust/dirt within case and power supply too.
From there, if CPU temps are high, cleaning an applying new thermal paste.
From there, running Memtest to test RAM to see if stick is failing, or try taking half your RAM out and see if issues still persist.