A 1080Ti should do it!
Okay, have you done a lot of customisation of madVR settings? Because a possible solution may lose those for you.
There were some Windows and madVR changes a while back that caused a number of people issues. The changes didn't work well together. Mostly Microsoft's fault I think. But anyway, the problem was fixed by resetting madVR back to defaults using the "restore default settings.bat" batch file in the madVR directory.
You may want to backup your "settings.bin" file before you do that, if there is one. Although the batch file does also does that.
The other solution available in recent versions of MC is to select one of the madVR Quality Presets in MC, at "Options > Video > General Video Settings > Load madVR quality preset". That will also overwrite most (any/all?) madVR customisations you have done.
In fact if I was having the issue you have with just a few DVDs, I would probably rest madVR to defaults and then test. If that fixed the issue, I would also select a quality profile to match my hardware, and test with that. In your case that would be the "High Quality" profile.
PS: RD is the expert in this area though. He may have some better advice.