theonerm2 :
I personally believe the Core i7 6700 is a better value than the Core i5 6600K. Secondly, since you're a gamer you will need more space than that SSD provides. Games are very large now so the more space the better. Also I know the power supply is overkill but that's one part you want to be overkill. Also the case should be overkill in my opinion. The parts you need to make overkill are the ones you can actually keep through many builds. If you have a good power supply you can upgrade your CPU and GPU without worry and you can keep a good power supply through more than one build. Same thing with the case. If you have a nice case you can upgrade your parts without worry and you can keep a good case to use through multiple builds.
Except its not. The 6600k can be overclocked and run at a higher speed per core. And the cores are the same, so other than hyperthreading which you don't need he gains no advantage for gaming at all. The 6600k will out game it any day of the week, admittedly the difference isn't huge but its there.
I do agree his storage is somewhat small but 480gb is more than enough to get him started and he can always add a HDD later, vs only having an HDD like you have which slows it all down.
Finally there is no chance he needs 650 watts, he has less than 400w worth of parts there, and the NEX series of PSUs is very low quality.
The build he already has will game better and run faster, there is no reason to do any of this.