I have a 3570k @ 4.0ghz so it's not a bottleneck. I've never had any FPS issues before in it but lately when I go into caves there are points where i have 0-10 FPS and it is unplayable. I put up the MSI Afterburner GPU monitor and I noticed that when it happens my GPU usage is dropping to 0-20%. This all fixes itself when I go back into open world where I get 80-90FPS and 110-144 in buildings. I don't have any dungeon/cave specific mods installed. I've re installed drivers and switched PCI slots. This only happens in Skyrim. Any ideas what this is happening?