The clock multipliers that the individual cores can reach is based upon a whole slew of factors, primarily including the number of cores active and the overall thermal headroom available. The BIOS defines the maximum clock multiplier that will be used by the active cores based upon the number of cores that are actually active. Some BIOS make this table available for modification and some don't. If you cannot find these configuration parameters within your system's BIOS, you will need to discuss this with your motherboard/system manufacturer.
For more information on the Turbo Boost feature, you can consult these sources (amongst others):
What is Intel Turbo Boost Technology and How Does it Work?
Why Am I Not Getting the Intel Turbo Boost Frequency?
My Intel Core Processor Does Not Reach the Maximum Turbo Boost Frequency
Frequently Asked Questions for Intel Turbo Boost Technology
Frequently Asked Questions About Temperature for Intel Processors
Hope this helps,
...S
