Hello, i don't now about computers, so i need help
i want to buy this
i5-2500K Sandy Bridge 3.7GHz Turbo LGA1155
Asus M5a99x Evo Am3 P/amd Fx Usb 3.0 Y 2.0 Sata 3gb/s
Ddr3 Gskill 2x4gb Kit 1866mhz Sniper 8gb
Ati 5670 1 Gb Ddr5 Dvi Hdmi Pci-e
Cooler Master Gx 750w 12v 60a
Western Digital Caviar Black 640GB SATA 2
7200 RPM 32MB CACHE
I actually have this
ram 2046 MB
AMD Athlon 64 X2, 2900 MHz (14.5 x 200) 5600
gforce 9500gt 512mb
That motherboard will not support an Intel chip. You will need to purchase a Intel supported motherboard, probably "H" or "P" series. Everything else will work just fine, I'm sure you will get many other responses suggesting specific hardware and configurations.
Edit - look for a motherboard that supports "1155 chipset"
h-series intel MBs do not support OCing to the extent of P, Z and X series boards. if you want to get the cheaper H-series get the non-K cpu's. as rage pointed out, if you're going to get a sandy bridge (not SB-E) you're looking at 1155 socket CPUs