one more thing is that i found that gtx 550ti ZOTAC,have PCIe 1.0 and 2.0 ,then should i buy mobo which having pcie 3.0 tech.?and i choosed i5 3550 3 gen.
i am in big confusion that which pc i should buy
If your planning on upgrading, if your going to spend the money yeah go for a mobo that supports the latest stuff so you wont waste money upgrading again.
Go for LGA 1155 Z77 chipset with the cpu you chose. Its always good having the option for future upgrades.