CPUs priced over $220 offer rapidly diminishing returns when it comes to performance in games. As such, we have a hard time recommending anything more expensive than the Core i5-3570K, especially since this multiplier-unlocked processor is easy to tune up to 4.5 GHz or so with the right cooler. Even at stock clocks, though, it matches or beats the old $1,000 Gulftown-based Core i7-990X Extreme Edition in game tests.
We have seen a small handful of games benefit from Hyper-Threaded Core i7 processors, though. Because we believe this is a trend that will continue as developers optimize their titles, we're including the Core i7-3770K as an honorable mention, now selling for $320. In a vast majority of games, the Core i7 won't demonstrate much advantage over the Core i5. But if you're a serious enthusiast who wants some future-proofing and values highly-threaded application performance, this processor may be worth the extra money.
In addition, there's certainly an argument to be made for using LGA 2011 as the ultimate gaming platform. LGA 2011-based CPUs have more available cache and as many as two more execution cores than the flagship LGA 1150/1155 models. Additionally, more bandwidth is delivered through a quad-channel memory controller. And with 40 lanes of third-gen PCIe connectivity available from Sandy Bridge-E-based processors, the platform natively supports two x16 and one x8 slot, or one x16 and three x8 slots, alleviating potential bottlenecks in three- and four-way CrossFire or SLI configurations.
Although they sound impressive, those advantages don't necessarily translate into significant performance gains in modern titles. Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1,000 LGA 2011 Core i7-3970X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines.
Where we do see the potential for Sandy Bridge-E to drive additional performance is in processor-bound games like World of Warcraft or the multiplayer component ofBattlefield 3. If you're running a three- or four-way array of graphics cards already, there's a good chance that you already own more than enough rendering muscle. An overclocked Core i7-3970X or -3930K could help the rest of your platform catch up to an insanely powerful arrangement of GPUs.
To summarize, while we generally recommend against purchasing any gaming CPU that retails for more than $220 from a value point of view (sink that money into graphics and the motherboard instead), there are those of you who have no trouble throwing down serious money on the best of the best, and who require the fastest possible performance available.
Although, its primarily written for gaming recommendations, its still worth a read
If multi-threading, photo editing e.t.c. is the kind of stuff you do, then go for a i7. Otherwise, i5 is a great option for almost everything.