Yes, big reason. A motherboard that supports a 6700K is NOT going to support a 9900 processor. Just because they are the same socket does NOT mean the board supports that cpu. The very first thing you do when attempting to upgrade a processor is to check the support page for the motherboard. That will list all supported processors.
Post the exact motherboard you are using and we can find all supported processors.
Post the exact motherboard you are using and we can find all supported processors.