It is
really locked at 30fps, not fluctuating? That is odd

Please post any mods, ini tweaks and system specs you got going.
Yepp. Locked at 30fps (Using fraps to display fps). If i restart Skyrim and load at the exact same spot, i'm back to 60fps.
It's not that my box can't handle the scene at 60fps at that place. Really odd indeed ...
As for mods, i only run some visuals like the high-res DLC and HD textures and foliage.
Here are my specs:
ASUS Maximus IV Extreme B3 RoG Edition Motherboard
Intel Core i7-2600K, Quad Core, 8MB L3 Cache, 1MB L2 Cache, 3.40 GHz (OC to 4.0GHz)
GeForce GTX 580 DS Superclocked, 1536MB (OC)
16GB Corsair DDR3 (OC)
I usually run the whole setup overclocked, but for testing dropped it down to the manufacturer specs just to make sure the OC didn't cause this.
Same result, game runs fine for a while (anywhere from 30 minutes to several hours) and then suddenly locks down to 30fps.
And it's always when switching cells, usually from interior to exterior.
I also checked the temps of the CPU, RAM and GPU when it happens and they are all fine, not even close to hot.
