Intel intros Extreme Edition 955 CPU, 975X chipset

— 11:30 AM on December 27, 2005

You can see a number of reviews around the web today of Intel's newest CPU and chipset combination, the Pentium Extreme Edition 955 processor and 975X core-logic chipset. The 955 Extreme Edition is the processor code-named "Presler," Intel's new 65nm dual-core CPU that has two chips situated together on a single package. This beast runs at 3.46GHz on a 1066MHz front-side bus and will sell for $999, like previous Extreme Editions. The 975X chipset's only real change over the previous 955X is the ability to split the north bridge's PCI Express lanes into two pairs of eight for CrossFire or SLI action (although NVIDIA hasn't validated the chipset for SLI... yet?)

We've had a review setup here in Damage Labs for quite a while now, but my penchant for last-minute testing efforts combined with some technical problems have delayed our review. The technical problems have to do with thermal throttling, as you can see illustrated in the screenshot below taken from the review system:

Click for a larger version
This setup gets too hot under load on our open test bench—with CPU temps up to 90 degrees Celsius—causing the CPU to resort to thermal throttling in order to cool itself. Of course, once we found this problem, we had to throw out all of our benchmark results, because they would be invalidated by the presence of TM1 throttling, which can really hamper CPU performance.

Having spent a number of hours troubleshooting this issue, I don't think it's straightforwardly caused by a CPU that runs too hot. In fact, we found the problem to be worse on the same Intel 975X-based motherboard with an older Extreme Edition 840 processor that we know to be sufficiently cooled on a different motherboard using the exact same cooler. The problem appears to be caused by the way the Intel 975X mobo is reading and reacting to thermal data from the CPU and thus controlling the fan speed of the stock Intel CPU cooler, although these things get complex enough that I hesitate to pinpoint an exact cause. We are on our second CPU/mobo/cooler combination without a resolution. Intel says it is still working on a fix, and all I know is that this issue doesn’t look to be something that can be resolved by a simple BIOS update.

What I can tell you is that the throttling problems were easily resolved once I purchased one of these babies, a Zalman CNPS9500 LED cooler, and installed it on the system. With the thermal problems out of the way, I can proceed with CPU testing, so we should have a review for you later in the week or early next week. In the meantime, you may want to watch the reviews elsewhere on the web today carefully to see that they address any possible thermal problems and thus have been sure to produce valid benchmark results.

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