The ASRock site compatible processor list: ASRock > X99 Extreme4
Your processor is this one: Intel® Core™ i7-5820K Processor (15M Cache, up to 3.60 GHz) Specifications
You should be ok, provide you have the proper BIOS from ASRock to support your processor.
All standard disclaimers apply.
This message was posted on behalf of Intel Corporation
As Al Hill mentioned above you should be OK using the Intel® Core™ i7-5820K with the ASRock > X99 Extreme4. The processor is on the As Rock compatibility list and it is also on the Intel compatibility list with this motherboard.
You can see it here: