Needs help

im currently building a gaming computer cuz my comp is getting old and i want to play games that doesnt require low detail jus to play or lag like crazy

the parts that i picked out so far:

Asus P8Z68-M Pro

Seagate Barracuda ST31000524AS 7200.12 1TB SATA 32MB Cache 3.5IN

MSI GeForce GTX 560 Ti 448

Seasonic M12II 620W EPS12V 20/24PIN ATX Power Supply PFC 80+ Bronze Modular 6PIN PCI-E 120MM Fan

Intel Core i5 2500K Quad Core Unlocked Processor LGA1155 3.3GHZ Sandy Bridge 6MB

and i just need a RAM i was planning on getting this;
Corsair CMZ4GX3M1A1600C9 Vengeance 4GB 1X4GB DDR3-1600 CL9-9-9-24 Memory

i asked my friend who is a comp technician to make sure that the parts r compatible and he said at the ram isn't compatible with MOBO and asked another friend who is also a comp technician and he says it is so now im like wdf if anyone could give me a reccomendation on a ram for the MOBO or any improvements on the build that would be great. my budget is 1,200$CAD incuding taxes and stuff.
thx in advance

P.S i dont need a monitor, keyboard, mouse, os...