mobo/cpu/ram

hello, i am planning to build a new gaming rig that won't cost more than 500$. i am currently using the previous generation motherboard n780i, q6600(oced to 2.8gz) with corsair h50 liquid cooling and 4GB DDR2 and for gpu i have gtx 560ti galaxy. i want to build a sandy bridge (i5,i7 etc)...