The i7 7700K will run at 4.5Ghz (turbo boost) in big loads. Take it, Bit will be happy...:lol:
The B250 has only 12 lanes available for the PCI-e configuration. The NVMe PCIe SSD use 3 lanes, so only 9 lanes remain for the video card. Your video card don't use more than 8 lanes but if you addition a SSD later, get a SATA SSD. Samsung SSD are the best, Crucial MX300 are very good.
The only problem with the RAM... There is a chance, if you add more stick, they will not work with those already installed in this pc. Even if you get the same model/company. You need 16GB to run DCS properly.
It's always better to have 2x8GB instead of 2x4GB now and 2x4GB later.
The peoples takes the risk, i only want to warn you.
Congrats for your new pc.:thumbup: