Before we can do a conclusion, again we give you the overall scores. Of course the i7-870 is faster compared to the i7 920 due to the higher clock. If you consider the higher turbo, when enabled, then the i7 870 will match the i7-950. The dual-channel memory interface does not limit its performance.
We have told you that hyperthreading can hurt performance. To illustrate this behavior we have benched x264 with hyperthreading enabled and also run the bench with eight threads (8T). Hyperthreading and eight threads pays off only in one bench.
To give you a better overview we compare system costs. We calculated the cost of the used mainboards, CPUs and graphics-card and also the lowest possible price for a 4GB kit for dual-channel or a 3GB kit for triple-channel. Memory of course PC3-12800 (1600MHz) with CL8-8-8-24 and PC2-8500 CL5-5-5-18. Last week we saw an increase of prices in the DDR2 market, which does hurt AMD a bit. So the overclocking memory settings may not apply but it gives you a good overview. The Q9450 is not longer readily available, and if you find it, you'll find it at horribly high prices, so we used Q9550 pricing. As we have written in our AMD Phenom II 965 Black Edition review this CPU is too expensive, but so is the i7-750. You get the best price/performance ratio with an AMD Phenom II 955 Black Edition running on a DDR2 board but the i5-750 is also very close in overclocked settings.
For some reason Intel thinks we need an i7-870. The i7-950 is priced equally so you can choose if you take either an dual-channel or triple-channel board. The naming scheme will confuse customers while performance is on par.
The i7-870 is priced €459,- that's a tad more expensive as the i7-950 which costs you €454,-.
Users who know their applications will not be hurt by hyperthreading, can choose this CPU, but for the normal customer we don't see any reason. The i7-870 costs nearly three times as much as an i7-750, but it only delivers a mere 4% performance increase (without turbo).
On the other hand Intel is cannibalizing the 1366 market. Apart from more PCIe x16 lanes with a X58 board, there is really no reason whatsoever to buy a 1366 platform.