Alright so first things first - I'm running a rig with these specs. All of them are at stock clock speeds. The i5 idles at around 30C, and runs under stress at 45c at the absolute hottest. The 6850 idles at around 39c with the fan at 100% and runs under stress at around 60c at the absolute hottest.
Intel i5 2500k
8Gb G-Skill RAM
AMD 6850 1GB
Asrock Extreme 3 Motherboard
Seagate 1Tb 6b/s HDD
I am experiencing about 10-15 FPS with all the settings on ultra. A week ago I was playing with 45-60 FPS on ultra with absolutely no problems whatsoever.
Now the story goes this way: I am asleep, while my gf plays skyrim. All of a sudden she wakes me up, and says Skyrim started lagging really badly out of nowhere. And it was. It went from perfect performance to terrible 10-15FPS while in-game when she transitioned from an interior cell to an exterior cell. Now its NEVER done this before and had an easy 45fps in an exterior cell only an hour ago, when I was playing. She swears up and down she didn't modify anything.
Since then, I've done 3 installs of skyrim. All of them clean. All of them where I hand-picked the mods and organized them with the assistance of BOSS and my own knowledge of the mods. The FPS hasn't improved at all. The only thing that has improved the FPS is turning all the settings down to Low. But the thing is, it ran them on Ultra perfectly fine a week ago. That is - Ultra with Skyrim HD mods and other graphical improvement mods. Now the game barely scrapes by at 40fps (ON THE HIGH SIDE) with the graphics on low with zero mods active.
I have updated Windows 7, I have updated my graphics card drivers, I have made sure the large address aware tag is ticked on the skyrim.exe, and I've googled and googled to no avail.
I'm really at a complete loss here. What happened, and how can I fix it?