idle, not sure how to verify it under load
I'm and AMD guy so I'm not 100% sure on intel stuff, but I would be shocked if intel CPU's didn't down-clock at idle like AMD's do.
My 1045t is OC to 3.4Ghz and idles at a little over 1Ghz. (So that's what CPU-Z shows when it's not doing much work)'
Run CPU-Z and then also run something like prime95.
You will probably see the speed jump to 3.4 (or whatever the max set speed is) and stay there.