Intel Updates Nehalem: Core i7-975 Processor Review
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The Fast and the Faster
Nehalem Thus Far
Intel’s Nehalem microarchitecture has been living in the lap of luxury since November of last year when the first three processors of the Intel Core i7 line were released. At that time we saw the Core i7-965 Extreme Edition, i7-940 and i7-920 brought to market with a few motherboards based on the brand new Intel X58 chipset. Performance was outstanding but prices were high, especially when including the motherboard and triple-channel memory requirement.
I won’t dive too far into the architecture design on the Intel Core i7 quad-core processors, but there are a few key features that make the Core i7 unique in comparison to the Core 2 line. Though the core itself shares a lot of the logical design with the Core 2 parts, the Core i7 saw performance enhancements thanks both to the introduction of the “uncore” and the reintroduction of HyperThreading to allow for two active threads on each core. The “uncore” portion of the Core i7 includes an on-board memory controller, the first triple channel solution, the QPI (Quick Path Interconnect) link to the chipset and other CPUs in multi-socket systems, power management and more. Another boon for Core i7 performance is a feature called Turbo Mode that allows the frequency of the CPU to scale higher when thermals allow. This essentially allowed the processor to run at higher with single or double threaded software while maintaining good performance for more heavily threaded applications.
If you want the full run down on the features and tech details on the architecture, you should definitely check out my previous Nehalem article from last November.
For the first time since the November release, Intel is making changes to the Nehalem desktop market by dropping a pair of the CPUs but replacing them with faster models.
Intel Lynnfield (Core i5) is still MIA
One thing that we, and the rest of the PC community, have been waiting for is Intel’s Nehalem architecture to reach the mainstream market with the processor codenamed Lynnfield, commonly referred to as the Core i5 (we are still just guessing). Lynnfield will offer the same quad-core design with HyperThreading on some models (low-cost models may not include HT support) while removing one of the DDR3 memory channels and integrated 16 lanes of PCI Express 2.0 on to the chip itself. The chipset market will get a dramatic shift as X58 (still a two chip solution) makes way for the P5-series that will be a single chip solution for I/O and a DMI connection to the CPU.
This all adds up to a lower cost platform – something enthusiasts would clamor for. But the delays keep mounting for Lynnfield and the debate wages on whether these are technical delays on the CPU itself or political delays due to a huge amount of Core 2 and P4-series chipset products sitting in the channel. Either way, I think we’ll be lucky to see wide availability of Lynnfield before September/October and thus the Core i7 becomes a more attractive option for users looking to upgrade soon.
The Core i7-975 and Core i7-950 Processors
Today Intel is officially releasing a pair of new additions to the Core i7 line of processors while slowly removing another pair. On the chopping block are the Core i7-965 Extreme that runs at 3.2 GHz and the Core i7-940 that runs at 2.93 GHz. Replacing them is the Core i7-975 which will operate at a base clock of 3.33 GHz and the Core i7-950 that runs at 3.06 GHz. The speed is modest – only a 133 MHz on each part – and the real belle of the Core i7 ball, in most enthusiasts’ view, the Core i7-920, will be sticking around at that same speed and price point.
Other than the frequency increase, little to nothing has changed on the 975/950 Core i7 parts officially though we are hearing that some minor tweaks were done to the memory controller on the chip allowing for higher DDR3 memory overclocking. As is usually the case for both Intel and AMD, when a new chip is released it’s unlikely that the engineers were not using their time wisely by poking and prodding the process.
Update: I am hearing at Computex that one specific change in the 45nm high-K process was apparently tweaked to allow for a significant increase in overclocking headroom.
Turbo Mode works the same on the i7-975 as it did on the i7-965: the processor will scale a single bin speed higher when thermals allow it. In our testing, that was pretty much ANY time the CPU was loaded, whether with a single thread or eight. The 3.33 GHz CPU would run at about 3.5 GHz when pushed at 1.6 GHz at idle.
Obviously with so much being the same, you can likely predict that will happen in performance tests on these new parts. For my benchmarks I added the Core i7-975 (with Turbo Mode both enabled and disabled) to our wide list of results from November. I hate to spoil it for you – but the Core i7-975 is faster.
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