How will this build handle games?

it should run most games on high settings but not max. Pushing games to the maximum settings (with AA turned on and high res) is even hard for some SLI,Xfire configs. You should be fine though since the gtx 570 is a pretty good card.

I do recommend getting a radeon 7870 or a 7950 instead depending on how much you paid/will pay for the gtx 570. Better performance for the same price. Also you can get the 670 gtx if you have the monies. It will fare better on high settings. One last thing is consider the 3570k. If it only costs a little more, get that instead because you can overclock it for more performance.

Edit: oh yea consider getting an ssd for your os and a few games, although it is not necessary. It will help with boot and load times.
The psu is also way overkill unless you are planning on doing an sli config in the future.

Your PSU wattage is pretty high, you could go with a 600-700w and still SLI in the future, also you didn't mention which Asus z77.

You should be able to play most of the games or should i say 90% games without a problem. The only game that can ensure you is COD black ops 2

Play it! if that game works fine with ultra high setting then there is no question of part replacement

Also Try GTA 4, BF3 etc and check FPS

Is this all new parts or you are recovering parts of your current computer????

If it's all new parts, here is what I'll change :
- 900w PSU is way overkill. Get more like 650w-750w PSU. You will pay less and have room for future updates, like a second GPU. Antec is a good choice.
- Get i5 3570K instead of 3550. Faster even without overclocking, with overclocking, a really well spend 20$!
- GTX 570... It's not a bad GPU, but for the same price (new) or even lower, you can get a 7870 or GTX 660.
- You didn't tell your motherboard model number, there is alot of different Z77 board... Many here recommend Asrock for performance/value ratio but don't have experience with Asrock. I'm a MSI and Gigabyte fan, they are as good as ASUS with lower price.

^This

It also depends on what resolution you are going to be gaming at. Assuming 1920x1080+ (especially "+") the 570 will struggle a little with graphically intense games at max settings, you can probably tweak it to get mostly ultra/high settings though. Under 1920x1080 the 570 should hold it's own. If you are gaming at 1920x1080, and assuming you haven't bought these yet, you may want to look at a 7950 or 670 if you can go that high money wise.

Im buying this build from somebody for 800, including monitor