CTurbo :
The e3 Xeons are based off of desktop i7s and in a few instances, i5s, but the e5 and e7 Xeons are not. Some of the Xeons like the e5-2687w would be great at gaming, but it's +$2000.
There are only 5 different Sandybridge silicon dies that I am aware of (some have more than one stepping though). Ivybridge and Haswell are a bit more spread out, but not significantly so.
The famous six core 3930k and 3960x are fabricated as 8 core microprocessors with 20MiB of L3 cache, 40 PCIe 3.0 lanes, and 2 QPI links. In some products a pair of cores is disabled, along with a varying amount of cache for yield reasons. Two different 3930k chips may have different cores disabled. The QPI links are disabled on all of them for marketing reasons so that they cannot be used in multi-socket configurations. This is also true for Xeon E5-1000 series microprocessors. The 3930k is the exact same silicon design as the high end Xeon E5-4650. The i7-3820 is a native quad core that shares the same silicon as all other quad-core Sandybridge-E variants.
There are no Sandybridge E7s, and there are more die variants for Ivybridge, especially with the brand new 15 core behemoths, but chips of similar core count and architecture are almost always cut from the same silicon.