Background: I built a 18 core machine 2 years ago to serve as my CAD render workstation. It works great for rendering, but there is this weird irregular errata that happens with the machine. I have been trying to pin point it ever since. It seems to come up every few days. machine specs: -Xeon E5-2696 V3 QS (it's an engineering sample, latest revision before retail shipment) -intel 1.2tb p3600 nvme ssd -32gb (4x8gb) PC4-17000 2133mhz ECC samsung hp certified ram -quadro p2000 -silencer 750 psu -asrock x99 extreme4 motherboard -samsung 305t 2560x1600 lcd -dell u2410 lcd -windows 8.1 pro Problem: I will have 40 or so tabs open in the latest firefox, photoshop or Kicad running, and it will lag for about 2-3 seconds on clicking between firefox tabs. There is also distinct line tearing when scrolling down a page of text. Sometimes there is a delay between clicking windows. As you can imagine, there is only so much of this a man can stand before it drives drives him insane. The problem seemed to go away after a restart and them come back in a few hours or in a few days. I originally thought it was the quadro, so I used DDU and did a fresh driver install. That would occasionally, help, but the problem would keep coming back. I decided to give the system a windows memory test and it came back clean. I ran memtest64 and so far it has passed 3 rounds of testing with zero errors. I'm picking at straws here. I don't quite know what is causing this problem It seems that the ram is indeed ok. I am thinking my GPU might be problematic, but I don't have another gpu even close to the quadro to replace it with (last modern gpu I have is a radeon HD 5400). I am thinking of buying another gpu but I fear that the cpu itself may be suspect. A few weeks back, I was looking for xeon chips on ebay. One seller mentioned his E5 2696 v3 engineering sample had a "bad memory channel A" I have no idea how he came to this conclusion. https://www.ebay.com/itm/123980585136 Is it possible the integrated memory controller in my xeon is problematic or not finalized? Is there anyway to tell? If anyone has any input, that would be fantastic. Thanks Guys!