I can’t believe this was it! I was about to roll-back to windows 8.1 because of this but I thought, after searching for solutions for HOURS, “hmm, yesterday I upgraded to avast premium which has a firewall”. Googled “avast+DPC” and the thread was here. I was also using LatencyMon to monitor this and I though the culprit were the nvidia drivers, but no, it’s avast! Jesus… and this thread is 6 pages long! I feel like I should get a refund just for this crap!