Intel's first Core i5 and new Core i7s benchmarked

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By Darien Graham-Smith

Posted on 8 Sep 2009 at 05:00

Intel has unveiled three new CPUs, among them the first Core i5-branded processor. The Core i5-750, Core i7-860 and Core i7-870 are based on the new Lynnfield core and use a brand new LGA 1156 socket format.

Like older Core i7 processors, based on the Bloomfield core, the new CPUs each feature four cores on one 45nm die, with on-chip memory and PCI bus controllers. The 8MB of shared L3 cache remains too.

Click here for full reviews of the Core i5-750, Core i7-860 and Core i7-870.

But there are changes. The triple-channel RAM of the high-end Core i7s is exchanged for a more familiar dual-channel DDR3 system.

The three new CPUs have shown performance comparable to that of existing Core i7 processors, but they sell at distinctly lower prices.

And Turbo Mode – which dynamically adjusts clock speeds to give single-threaded applications a boost when other cores are underused – has been souped up. In Bloomfield a thread could be boosted only by a maximum of 266MHz, but Lynnfield can raise the speed of a single core by as much as 667MHz – a significant enhancement.

The three new models

Although the new CPUs are divided into one Core i5 and two Core i7 models, the only functional difference is that the Core i7 parts feature Intel’s HyperThreading technology, allowing them to act as virtual, eight-core CPUs. The Core i5 operates as a straightforward quad-core processor.

The other differentiator is, as usual, clock speed. The Core i5-750 has a nominal speed (disregarding Turbo Mode) of 2.66GHz, rising to 2.8GHz for the Core i7-860 and 2.93GHz for the Core i7-870. There’s no Extreme Edition on offer, so tinkerers won’t be able to tweak the frequency multipliers themselves.

In the PC Pro Labs the three CPUs have shown performance comparable to that of existing Core i7 processors, but they sell at distinctly lower prices – around £140 exc VAT for the Core i5-750 part, versus around £180 exc VAT for the Core i7-920.

Compatible motherboards are cheaper too (with many already available for below £100), meaning these could well be the chips that bring Nehalem into the mainstream.