noticed the same thing on mine, randomly spiking from core to core, no obvious pattern just totally random, unless you create profiles in Overdrive and tell it to run certain programs (Supreme Commander for example) on certain cores, that helps smoothness an absolute ton in that game I found, performance felt tons better even though Turbo Core is active, and should therefore be boosting frequency in that sort of application that doesn't use eight threads, but the random 'core jumping' somewhat makes Turbo Core not work all that well.
have you also noticed the peculiar non-linear scaling you get with frequency sometimes, where the performance % gained is higher than the % frequency increase? cache problem surely!
Edit: also not to go off topic too much, did you know you could fit 69 'Bobcat' cores onto a Bulldozer die, 320MM2 for Bulldozer, 4.9MM2 for Bobcat, lets assume that the number came down to let us say 48 bobcat cores, would a server processor with 48 of those cores not do more work with less power consumption than a one with eight Bulldozer cores, since isn't Bobcat faster, more power efficient and faster clock for clock vs. something like Atom, and since the server space tends to be very threaded, all those cores might pay dividends! even though I own a Bulldozer think Bobcat is AMD's true success story in recent times, that or Llano.
GPUs sub £100 are well and truly obsolete