Well I did just try it in game while in windowed mode and I caught a glimpse of it. While idling the core speed is at 1600 MHZ, but when I alt tabbed and looked at CPU-Z in game it was at 3500-3700. Is it supposed to be that low when idling and is it supposed to vary in frequency like that when actually using the CPU?
Turbo mode should engage when there is a load on the CPU and the load is limited to less than the number of cores on the CPU. For example, if you had a single threaded app on a quad core chip, it would run at the fastest turbo mode. More threads = more cores = less turbo speed. Its basically a way of using all the power available to the CPU at any given time when there is a load.
One thing I did notice that I thought was weird, but hopefully not a big deal, is when I did run prime95, cpuz showed the frequency at 3500 MHZ which is not what the boost cap is at. When I was simply clicking through folders, though, and going between applications, it did show it at 3800MHZ.
3.5 is what 4 Core max Turbo is (and that would be what you get in Prime 95). 3.8 is 1 Core max Turbo.
Interesting. I haven't noticed this because I have always run stress tests at an overclock with my 2500K. When you overclock, it forces all the cores to turbo up to the CPU ratio you set, right? But if you leave it at stock, it will do the 3.5 with all cores/3.8 with one core (with i7)?