Core i7 4770 runs at 3 GHz instead of 3.4 GHz

Hi,

I have a Core i7 4770 which I cannot get to run at 3.4 GHz.  Linux /proc/cpuinfo says:

model name      : Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

cpu MHz         : 2993.038

I think the 3 GHz comes from these BIOS settings: Host clock = 100 Hz and the CPU multiplier = 30.

But the BIOS doesn't let me change them!  So how can I get the processor to run at the correct speed?

Here are the hardware details (from dmidecode):

BIOS Information

        Vendor: Intel Corp.

        Version: MCH8710H.86A.0047.2013.0606.1508

        Release Date: 06/06/2013

Base Board Information

        Manufacturer: Intel Corporation

        Product Name: DH87MC

        Version: AAG74242-401

est