Manufacturer:Intel UK Price (as reviewed): Core i5-661: Around £150 (inc VAT), Core i3-530: Around £85 (inc VAT) US Price (as reviewed): Core i5-661: Around $195 (ex tax), Core i3-530: Around $120 (ex tax)
As soon as Intel announced Core i7, its amazingly successful range of Core 2 processors was living on borrowed time. With Core i5 and now Core i3, Core 2's number is finally up. The new Core i3 and Core i5 CPUs have a lot to live up but it’s a measure of how far Intel has come in the past couple of years that the direct replacements of the Core 2 lines are pitched as being Intel’s mainstream and budget-orientated parts.
As we’ve become used to since the Core i5 launch, the new Core i3 and i5 CPUs are intended to be slower than Core i7 – and considerably cheaper. That doesn't mean they're technologically uninteresting, though; they’re built using a 32nm manufacturing process rather than the 45nm process previous Core i5 and Core i7 CPUs used, and they also have GPUs built in. This is the first time we’ve seen a hybrid CPU/GPU processor.
Intel's current CPU lineup, from left to right: LGA1366 Core i7, LGA1156 Core i7, LGA1156 Core i5 and i3
Nehalem Rev 4
These new Core i3 and i5 processors represent the fourth generation of the Nehalem architecture, and share the same codename: Clarkdale. The Clarkdale CPU is very similar to the Lynnfield design of the first LGA1156 processors. It has an integrated PCI-E controller and an integrated, dual-channel DDR3 memory controller. But while the memory controller is rated at 1,333MHz, the PCI-E controller isn’t officially compatible with SLI or CrossFire. It still offers 16 lanes of PCI-E 2.0 bandwidth however, so it’s fine for a single graphics card, and we’ve heard about Clarkdale boards that claim to support SLI and CrossFire.
The new Core i5 processors are equipped with Turbo Boost (rev 2), so can increase their maximum frequency in certain situations. Turbo Boost works by shutting down unused execution cores and raising the CPU multiplier of those cores in use. By shutting down unused cores, the CPU doesn’t exceed its TDP or maximum power draw from the motherboard’s VRMs, so it’s a safe and power-efficient overclock that’s applied on the fly. The new range of Core i3 processors do not have Turbo Boost enabled, but the Core i5s do.
Clarkdale CPUs have the usual 32+32KB of Level 1 cache (for data and instructions) and 256KB of Level 2 cache per core. However, while the earlier Core i5-750 has 8MB of Level 3 cache, Clarkdale CPUs have only 4MB of Level 3 cache.
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All of the new Core-branded Clarkdale CPUs support Hyper-Threading, but as they’re all dual-core CPUs this means that you’ll only see four execution threads in Device Manager. Remember that the Core i5-750 is a quad-core CPU with no Hyper-Threading, while the Core i7-860 and i7-870 are quad-core CPUs with Hyper-Threading. Clarkdale also introduces six new instructions, including AES-NI (Advanced Encryption Standard New Instructions) that according to Intel "may help speed up applications that use the AES algorithm".
Intel also claims the new 32nm CPUs have a faster Virtualisation access latency, which should certainly benefit, especially for future workstation products, and while the Power Control Unit function is largely the same, the response latency and power gating have also been improved.
There’s also a new range of Pentium CPUs based on Clarkdale that don’t support Hyper-Threading. We don’t have a sample or many details about these new CPUs, but have included them on both the pricing table and the feature fables for the sake of completeness.
All of the new CPUs fit in the LGA1156 socket, so the fears that Core i3 would introduce yet another socket to supplement LGA1366 and LGA1156 were misplaced. Existing P55 motherboards should work with any of the Clarkdale CPUs as long as they’ve had the correct BIOS update. However, Clarkdale CPUs are really intended to fit in motherboards sporting one of the three new Intel chipsets, the H55, H57 or Q57. These motherboards all have display outputs built in to make use of the integrated GPU.