Check out these quotes from Intel Core i7 870 reviews & previews
"The Core i7-870 represents the best Lynnfield currently has to offer. Needless to say, my expectations were quite high. When it comes to performance, though Intel delivered. The i7-870 consistently topped the charts, even outpacing the Core i7-920 in several benchmarks. Without a doubt, this is the Nehalem-level performance Intel promised."
"It's hard not to admire Intels R&D department as just when you think things cannot get any faster, they go and prove us all wrong. While the i7-8xx range is hardly as groundbreaking as the original Core series, nobody can dispute that Intel have waved their magic wand over the Core series refresh and by trimming the expensive fat from the obese 9xx series they have packaged a product more affordable for the masses."
"In my opinion, the new Lynnfield Core i7 processors are a very good step in the right direction. Through testing and benchmarking, when compared to a Nehalem system, the new Intel i7-870 packs a lot of punch for the dollar. Performance differences with the Turbo mode enabled yielded performance numbers near or slightly behind the much more expensive i7-965XE previously reviewed HERE. For almost half the price, the performance is pretty good for a mainstream option and with the motherboard and memory options being cheaper as well, the new i7-870 Lynnfield processor will be a good alternative to the much more expensive Nehalem. The performance for the dollar makes this quite a fast mainstream focused processor.
I can't see any real reason why you should pick this processor up for your next upgrade. It performs pretty well for the money, it will be a good overclocker, it runs relatively cool and still keep up with processors worth almost double the price. Seems like a bargain for the power user to me."