If you don't already have a motherboard and are only interested in the best gaming performance for the money, check out offerings from the AM3+ AMD chipsets. They are typically just a hair behind Intel in the gaming experience, but can be had for a lot less money.
My primary rig is an FX-8350 based system and I have an i5 based system (3570k) for a while. For the most part, they were nearly identical in gaming. Some games favored the AMD others the Intel. When streaming the 8350 won out and for most productivity like rendering.
That being said, the Xeon is a very good deal. You get i7 performance for the price, or a little more, than the i5. It would be about the same maybe a bit better in gaming and would absolutely stomp it in productivity. That is why, for my mITX system I'm building, I ordered the Xeon. You really need to go with Intel in that form factor and considering I won't be doing an OCing, because I want a very quiet and very cool system that I could play games and render on, I went with the Xeon.
For the most part though, you can get by with an AMD based system. Despite all the rampant fanboyism, AMDs CPUs aren't miles behind Intel's The 8350 is an excellent chip and does well in gaming and productivity, especially if the program is well threaded and can take advantage of all those cores.
Exactly. If we were talking about other processors he would want, an FX processor would be the best price for solely gaming (and even video editing). However, if we're restricting to Intel builds, the i5 is the best for gaming as the i7 doesn't improve much for games for what you are buying.
The Xeon v3 is practically a slightly lower-clocked i7 4770 without an iGPU. If you need productivity work done, that is the best price/performance CPU, and it can do gaming quite well. You can do FSB overclocking with it too if the MB supports it, but it isn't multiplier unlocked like the K series, so be prepared to fiddle with the RAM clock as well if one plans on overclocking.
I have the Ivy Bridge version of that CPU (E3-1230 V2) in my gaming/productivity rig. I've never maxed it out playing any games, and the highest I've seen it go was only about 40% or so. It's extremely stable too.
+1 here for DerKrieger: i dont know anything else to say. ☺
The Xeon is basicly a realy nice chip, with its 3.7 turbo clock. and HT for just a few bucks more then an i5, for productivity like DerKrieger allready mentioned, the xeon will be a lot better then the i5. the 3.7 ghz turbo clock, is basicly fast enough, for anything. so yeah if you look for a nice small silent productivity / gaming rig , i would realy concider the Xeon. If you dont care about formfactor then the FX8320 or FX8350 is also a great choice for productivity and gaming.