I re-downloaded GTA IV and tried the borderless program. Its so close to fixing the issue! I get smooth performance for about 5 minutes, and then stuttering begins. If I hit F4 to refresh the window, the game will once again be smooth for a few minutes. This program lets me refresh the game with one button, which does make the game more bearable. I really want to figure out why this stuttering is occuring; even with borderless window mode.
I didn't have this issue a few weeks ago with the same AMD drivers... The only software change I can think of was the large Steam update.
Here is a screenshot of the stuttering issue documented using MSI Afterburner. This is before I alt-tab/toggle v-sync/refresh the window:
Frame times are crazy and the game is a mess.
Here is a screenshot of the same area the character is in, but
after I alt-tab/toggle vsync/whatever:
Everything across the board is smoother including GPU voltage changes and frametime + framerate. This will last for a random amount of time before stuttering will set in again.
I'm pretty puzzled at why this is happening.
Edit: It's Steam! Running GTA IV without Steam in the background fixes the issue. The GPU is acting normally; Steam must be causing something to cause frames to be skipped after a random amount of time. I disabled the Steam overlay with GTAIV launched normally, but the only true fix is to not have Steam at all...
The GFWL overlay still behaves normally.