Xeons are typically better binned cpus hat are mainly different because they are designed for multiprocessors systems (dual QPI) that are usually equilavent to desktop enthusiast I3/I5/I7 chips
Some Nehalem Xeons are good overclockers though usually their motherboards dont support it
Unless your running a multi cpu workstation for rendering,encoding,ray tracing etc
then much better off with enthusiast cpus due to the xeon workstation mother boards being limited (No SLi?CF, no overclocking etc)
CPUs are like tools
they each are designed for specific purposes
The only reason I could see a "gamer" buying a xeon processor is if they are using evga's sr-2 which is really just overkill and will not be utilized fully for just gaming and is very expensive. And other than the extra QPI they are the exact same as the desktop chips as mentioned above.
Xeons are perfectly good for gaming but do have some drawbacks as mentioned further up in the thread.
Unless you spend a stupid amount of money on an after market MOBO to over clock them, you cant. To buy a xeon with even a 3.0ghz + stock speed is nuts money, as they design these chips to run 24/7 365 days a year at 100% load. They are also much better in running VMware or other virtulization platforms.
For the cost of a modern Xeon CPU, which have there prices jacked because they are aim at the commercial market, you could build a high end gaming rig using consumer products.
You will notice the rig I have under my profile is an old dell precision workstation which is packing two xeon dual core chips, this works fine for me as a World of Warcraft rig, and I can run the game on just under ultra settings at 1600 x 1200 resolution.
In short, I wouldn't spend your money on a new Xeon chip and system as you wont get the "value add" from the system, unless as mentioned earlier, you use the PC for graphics and encoding, but a Xeon system only overtakes desktop PC's in this area when you have more than one Xeon chip in the set-up, thus utilising more logical and virtual cores.
Getting to the bottom of this thread i have just realised your not planning on buying one............. anyway you get the point
To answer your question directly, the gaming performance of a Xeon equivalent i7 will not differ by much, if at all with regards to solely gaming, seeing as as said above, Xeons are just higher binned i7s which are 'designed', in a sense (really they're more reliable as CPUs) to run in much higher workload situations.
First of all because Intel uses a unified microarchitecture across almost all of our CPUs there is very little difference from one processor in the same family to the next. So a 1st generation Intel® Core™ I7 900 series is very much like an Intel Xeon® 5500 series processor, except that the Xeon has the ability to work in a dual processor configuration. So when it comes down to performance for gaming the biggest difference is what the board supports. Since we haven’t release a Xeon with the 2nd generation architecture yet… Any Xeon you were to buy right now would have the older technology behind it and wouldn’t perform as well as a new Intel Core I7 2600K. One more thing is that most games wouldn’t take advantage of the extra threads that dual Xeons system would give you.