What happens if you go back to a stock speed instead of overclocking?
That was part of the plan upon receiving back my computer. I was tested stable at 4.6.... but I'm starting to have my doubts.
Autosave has always been unreliable for me, for the last three versions of Premiere, at least. It works fine for days, then for no obvious reason just stops.
I tend to check for autosaved versions after editing for a while and if there are none, a Save project, turn off Autosave, Save project, turn on Autosave, Save project restores its operation for that editing session, at least.
That's a bummer. Your system sounds really nice when it all works, though!
I've just had my first problem with Premiere CS5 on my system in many months. Editing a feature film shot on 5DMkII, 7D and D7000, and the entire system got real sluggish. At first, rebooting seemed to fix. I was about to up my RAM from 16GB to 32GB, when I remembered to try holding shift+alt when launching Pr to erase the preference file. That solved it completely for me, so I can save my RAM money for later.
I've also found Pr isn't that swell with lots of stills, whereas AE is amazing. I had a project using ~70,000 stills (16.2 megapixel each) in a timelapse, panning and zooming around the entire array of photos. Pr choked when the number of stills reached 4-5 thousand, but After Effects handled all 70,000 with no problems. Maybe worth trying your effect in AE instead.
Never had the autosave issue. That really is a drag. Anyway, hope you sort it out!