Those are a bit overkill for a gaming pc. Also, you should build it yourself, you will save money.
Agreed, those computers will run anything you throw at them but that doesn't necessarily make them good buys. Straight off the bat you could build the exact same systems for less. Second you could tune it the way you want
Yes I would highly suggest to build your own pc, you will save TONS of money. And too start you off go on pcpartpicker.com.