Ok, I've been running various tests all week so I think I can give you some decent input. My specs:
Intel Xeon E3-1241 V3, 3.5GHz Quad Core
Asus Z97-A motherboard
G. Skill Ares Series 16GB DDR3-1600 Memory
Asus R9 280, 3GB
Skyrim is stored on a WD Black Series 2TB, 7200RPM HDD
Windows 8.1 64 bit
AMD Driver 15.9.1 Beta
Testing with: vanilla ini's + Skyrim set to Ultra + Bethesda Hi-Res DLC Optimized (1K full replacer version) + all unofficial patches (except high-res dlc) + DynDOLOD on High + ENBoost... I get a consistent 60 fps no matter where I go in the world running at a full sprint the entire time. The only exception is when I 'coc Whiterun' and run past the companions fight with the giant. That scripted fight will drop fps by 3-5 even when on a pure vanilla setup.
I would suggest you change your testing method. The intro sequence is known to be heavily scripted and I believe even disable objects during it. Try this instead:
On the start screen enter the console (press ~) and type 'coc whiterun'.
Once there, turn around towards Whiterun, give things a minute to load then enter the console again and type 'tgm' to toggle god mode so you can sprint indefinitely.
Take off in a full sprint down the road past the companions fight and when you reach the stables turn to run into the plains area. Just run through there a while and monitor your fps and let us know what you get.
I would also suggest, as was already stated by z929669, to refresh your ini's to get vanilla ones. I would uninstall ENB and ENBoost just to narrow down any issues and to rule them out as a cause. I would even run the game directly through the launcher to narrow it down even more. Keep Vsync ON (see note #2) during this test run. Let the launcher detect your video settings and do not worry about a Catalyst Control profile for Skyrim at the moment. It's just one more thing to take out of the equation. Once we have you up and running in a pure vanilla setup, then we can go with the STEP recommended Catalyst Control settings and see what happens there... then ENB... then anything else. One step at a time is what we want to shoot for here.
Note #1: Since some recent driver update (not sure which one but it was pretty recent), I have started to experience the graphical issue where I get black lines around fires and fire spells. Check for this by running over to a giant camp and looking above the fire during the day. It's easy to spot if it's there. To fix it, lower your AA from 8 to 4.
Note #2: I think Skyrim is not the best choice to test out your new card's abilities due to it apparently needing Vsync enabled. There are plenty of threads discussing how physics and everything else gets all jacked up when it is turned off. See here. I'm assuming this really has a huge impact on the intro scene. I would try to do a comparison on a different game.
Edited by ToggleAI, 11 October 2015 - 07:18 AM.