For CPU (and basic memory), run LinX in two modes: 1) Memory (MiB) - at least 50% of your total RAM, even better - 24Gb+, run 5+ time(s) or for at least 30 minutes; 2) Memory (MiB) - 2048 (or 3072, your choice) for at least 30 run(s) or, well, 30 minutes. Also, CineBench and Prime95 "Small FFT" (very recommended for thermals).
For GPU: Unigine Heaven (loop for 30+ min), Unigine Valley (same), obvious FurMark or MSI Kombustor.
For RAM: TestMem 5 with "extreme" preset by anta777 (at least one full cycle or 3 hours, more - better; must have ZERO errors); Prime95 "Large FFT" (make sure "Run FFTs in-place" is UNchecked) for at least an hour.
If all these fail to detect an issue, the problem might be total power consumption spikes (very unlikely, but whatever). Also, I guess you already tried reinstalling chipset drivers and audio drivers, but still have to mention that.
Finally, try finding a whatever GPU, even if gt1030 or alike, to just replace yours and see what happens.