intel I5 or AMD 8320 cpu
660 or a 760 from NV
270(x) or amd 280 which is getting cheap or a 285 which is pretty new
These cards are overpowered for what you listed for games but sometimes you want to dial up the settings.
An AMD 265 or a NV750ti would both be enough for you but sometimes tastes change and moving up settings is addictive. New games come out and you always want to keep up at the very least.
Want is the enemy of a builders. I cheaped out before and regretted it for a few years. When I finally upgraded again I spent the money and actually bought what I wanted.
I occasionally build and sell.
For what you have listed for games.
an i3 and a 7790/r7 260x would be good enough and quite cheap.
It leaves you with tons of room to upgrade. When you have locked cpu's don't waste cash on expensive motherboards. Find a cheap one with most of the features you want.
Internet cafe's usually don't have 1300 dollar setups. What I suggested below could get you approximately 2 machines that meet you graphics requirements. Above would cost about 800 per machine.
Antec NEW SOLUTION SERIES VSK-3000 Black
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129186
Seagate Barracuda ST1000DM003 1TB 7200 RPM 64MB
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148840
EVGA GeForce GTX 750 Ti Superclocked 2GB
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487024
CORSAIR CX series CX500 500W ATX12V v2.3 80 PLUS BRONZE
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027
Patriot Viper 3 Low Profile Blue 8GB (2 x 4GB)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820220836
MSI H81M-P33 LGA 1150 Intel H81 SATA 6Gb/s USB 3.0 Micro ATX
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130731
Intel Core i3-4150 Haswell Dual-Core 3.5GHz LGA 1150 54W
http://www.newegg.com/Product/Product.aspx?Item=N82E16819116995
Subtotal: $522.93
These come to 520 minus rebate. Tack on the windows license and they come out to about 600 even. Buy the license directly from MS or a local retailer for a multi machine license. Get a deal.
If you don't like it, I can spend the full 1300 per machine for you, proper.
If you choose this option I`d love to come play games at your café. 1300 dollars far exceeds your requirements.
If you take either of my builds I would hope I could at the very least have access to your gaming server if you plan on building one.