An i7 is overkill for almost every game, you're better off buying an i5 and using the extra money to upgrade elsewhere (maybe up to a 1080?) or even just saving the money. i7's are really only needed for video editing and processors that almost solely demand cpu power. If you look at pcpartpicker, where people post their gaming builds, you will see that even for high end rigs they are using i5's: click here (you can also use it to check compatibility, just click start a new build and enter all of your parts and it will flag any issues).
As for the PSU, I can't see it not working, but if it doesn't then you can always buy a new one, no point in buying one now only to discover that it would have worked with the old one.
I would also go for 16gb of ram, 8gb is fine but 16 is becoming standard for gaming pc's.
You will probably also want a large HDD to use to store your games, 1TB should be enough. As for sound card unless you are an audio freak you don't need one, and as with the PSU you can always buy one down the line if you want a sound upgrade.