The base frequency on that CPU is 3.40 GHz and the Turbo is 3.90 GHz. The specs are here. So yes you are seeing Turbo Boost.
Hello all! I just got a i7 4770 and I noticed in task manager it reports the frequency as around 3.8 ghz  when idle. The spec sheet sez the cpu runs at 3.4 ghz.I'm of course not complaining but it's weird. Is it the turbo boost doing that ? I don't think my i3 4150 ever went above the rated 3.5 ghz. Just curious.  
Haswell i7 question