i want to build a gaming pc my budget is $750
which cpu is better for under $750 with a good garphics card and what is difference between fx 8320 and fx 8350 if 8320 will be overclocked to 4.0ghz then it will perform same as fx 8350
8320 is identical to 8350. depending on the binning process though the 8350 would be a bit better silicon and might overclock to higher values. of course though, in practice, a overclocked 8320 at 4ghz is identical to 8350 @ 4ghz. depending on the exact cpu-s the 8350 could spend less watts to do that or could do it at a lower voltage.
if money is no issue, the 8350 is a better piece of silicon. if you're on a budget, 8320 is the better choice.
On a $750 budget, you may wish to drop back to a FX-6300 if it will let you get a stronger graphics card, unless your games are particularly CPU-dependent titles like MMOs.
Since you will likely want to overclock (if not, get an i3 instead), make sure your chosen motherboard is suitable. You'll want a true 900-series chipset board with heatsinks on the VRMs. Hooray, this is no longer blocked at work: https://spreadsheets.google.com/spreadsheet/pub?key=0AgN1D79Joo7tdE9xMUFlMEVWeFhuckJEVF9aMmtpUFE&gid=2 so check there for boards with known issues, like the MSI 970A-G4x.
Looking at your budget I think fx 8320 will a better option as it is somewhat an underclocked fx 8350. I would have told you to get fx 8350 if it was in your budget. But you can oc 8320 @ 4.0 ghz to get similar performance to 8350. But, 8320 @ 3.5 ghz and 8350 @ 4 ghz draw same 125w power, so oc'ing 8320 will be a bit more power hungry than keepig 8350 at stock frequency.
But, on upcoming 8 threaded games you may not necessarily need to oc 8320. So I think you should go for fx 8320 at that budget.
Go with an fx 8320 and put the extra into the graphics card like an r9 280x or something similar. Get a good motherboard like the Asus M5A99FX PRO R2.0 or Gigabyte GA-990FXA-UD3 so that you can overclock it
No, don't think of getting fx 8350 at the budget of $750. If you wan't a budget gaming pc which will give you enough price/performance then half of the money should be spent on cpu and gpu both, and the rest half should be spent on other comonents. So get fx 8320 as it is cheaper and well suited for your budget. And spend the extra saved money on buying a better gpu.
Hd 7870 or gtx 660 ti should go with your budget well. If not, there's not really much harm in buying gtx 660 as hd 7870 is only slightly better than it.
^My earlier point, although the FX-6300 may be the CPU to get to allow the stronger card. I've recently been subjectively testing a FX-8320 vs. a previous 970BE, but I'm not sure my usual games are sufficiently demanding for my results to be all that meaningful; a GTX650Ti handles all of them quite well.