Yes, it is recommended. When you attempt to support Turbo Boost Technology with Intel® Turbo Boost supporting processors, it is suggested to enable C-State in BIOS to obtain better performance if it is available.
For example,
One particular processor may allow up to two frequency steps (266.66 MHz) when just one core is active and one frequency step (133.33 MHz) when two or more cores are active. Therefore, higher deep C-state residency ("C3" or "C6") on some cores will generally result in increased core frequency on the active cores.


- Refer to Intel® Turbo Boost Technology
http://www.intel.com/technology/turboboost/index.htm?iid=tech_product+tb

Please make sure your CPU is Intel Core i5/i3 series with "Intel HD Graphics". First make sure the CPU is in the CPU Support list as the link indicated in CPU tag. Then check the CPU if "Graphics" support. For more detail about the CPU information. Please visit Intel Webstie. If your processor has no “Integrated Graphics”, you must install a PCI-E graphics card to get the display output. Otherwise, you may receive "no display" on this model. For more information about this behavior, please check out the Intel website below.
http://www.intel.com/support/processors/sb/CS-031174.htm

According to the datasheet of Intel 5 series chipset, "it can support up to two different images on different display devices". Therefore, the H55H-I V1.1 does not support 3 outputs of onboard HDMI,DVI,& D-sub working at the same time. It allows you to run any 2 of the onboard graphics simultaneously as below configuration based on Intel's spec.

According to the datasheet of Intel 5 series chipset, Intel graphics cannot be used along with an external PCI Express graphics controller. Installing a PCI Express graphics controller will disable Intel graphics. Please refer to the following website for more information about Multiple Display.

http://www.intel.com/support/graphics/sb/CS-031040.htm#8