Got my turntable hooked up recently, been really enjoying some old (read: original pressings) albums that were my father's.
It's a Technics SL-DL1 w/an AT-122LP cart, run to the PP2i, to the Fiio E17 to Senn 598s.
Clean the dust out of them. I had a similar issue creeping up when I had CFX 6970s, and a good cleaning solved the issue. Running multiple monitors will always bump the clocks up on the main card, but 70C is insane.
Check event viewer. Then sob and reinstall. This kind of thing happens to me (doesn't manifest quite this way) when I go stupid and try insane overclocks, think they're stable, and end up with a botched Windows installation a week later.
Nice job! We used to polish acrylic back in the day with stepped sanding or routing -- but instead of that plastic polish, you can also use a map gas torch to get to another level of clarity with a lot less time spent rubbing.