I'm running a Gigabyte RX580 on Windows 7 64bit and today I switched out my HDMI for DVI-D Dual-link. The HDMI went to my small tv that I'm going to be using as a second monitor (but it will only be used for watching videos/movies and will not receive active usage like my main monitor connected via DVI-D.
I mostly play old/Gog right now and as I switched the HDMI out I noticed that I get stuttering/lag in a game while also noticing that the "Fan Stop" (when the graphics card isn't working as hard) comes on and off periodically even as I type this post, nothing else is running only the browser. I had to turn down the settings on (old)games my RX580 should have no problem running. Prior to using DVI-D the "Fan Stop" would be constantly on and there would be no stuttering or lag in game.
Some background info:
I have the latest AMD drivers and I set my "Preferred Display" to my current monitor (DVI-D) if that makes any difference. As mentioned I also changed all my in-game settings to lower-medium settings and it appears to work with minimal stuttering. My screen resolution is 1920x1080, which was the same unchanged resolution used by HDMI.
Virtual Super Resolution: off
Radeon Freesync: off
GPU Scaling: off
Any help is appreciated, thanks.