Grimhaul,
If you’ve got an AMD card in that rig, can you give this a try for me? If you’re still having trouble after this troubleshooting, please generate a text copy of your DxDiag using these instructions. Once you have that made, open the file. You’ll need to copy and paste the contents of the Text document into the post using the “Code” button (</>). This will give me some more information which I can use to dig deeper into this case.