So i have over 100 hours put into skyrim on pc heavily modded i have been playing with Real Vision ENB, 2k texture packs ane several other graphical overhauls with out any problems between 50-60 fps for the most part sometimes dropping to 40 in demanding areas. But the other day when i to play it was perfectly fine for about 25 minutes then all of sudden my frames went down to 8 fps i didnt change anything add any new mods or do anything unusual but now where ever i go my fps are between 8-12 no matter what im doing what could this be? Im running on windows 8 with a gtx 780 and an intel i7 3770. Btw this hasnt seemed to effect any other games