Vital Signs & Overclocking
On the surface, the Pentium Extreme Edition 965 looks just like any other LGA775 based Intel processor. Other than the unique marking etched into the processor's integrated heat spreader, there is nothing that would set this chip apart from its predecessors.
The Pentium Extreme Edition 965 is equipped with the same integrated heat spreader and packaging as previous Pentiums, but underneath that heat spreader are two distinct Cedar Mill dies (two Cedar Mill dies = one Presler), connected through the processor's packaging substrate.
If you recall from our previous Intel coverage, the Smithfield core used on the Extreme Edition 840 was basically two Prescott cores linked together to form one large die. Incorporating two individual dies onto one package with the Presler core though, should help Intel with yields on the 965XE and other dual-core Presler based processors, because the dies can come from two different parts of the same wafer, or even two different wafers altogether.
Due to the fact that this is a dual-core CPU, and each individual core has Hyper-Threading enabled, the 965XE appears as four virtual processors in a supported operating system, like Windows XP. Each core is clocked at 3.73GHz and rides on a 1066MHz front side bus (266MHz quad-pumped). Each core is equipped with 2MB of full-speed L2 cache, for a grand total of 4MB. The CPU requires a mere 1.2v - 1.33v to operate. We should also note that the Pentium Extreme Edition 965 has full support for Intel's Virtualization technology, which gives users the ability to run multiple operating systems in independent environments, full support for EM64T to run 64-bit operating systems, and the Execute Disable Bit to prevent certain types of malware driven buffer-overflow attacks.
What you can't see without the help of some software is that the Pentium Extreme Edition 965's Presler core is also a completely new stepping. If you look back at this image from our 955XE article, you'll see that the 955XE used stepping "2". However, the Pentium Extreme Edition 965, while part of the same family of processors, has a stepping designator of "4". Stepping "4" incorporates the C1E halt state, that lowers clock speeds and power consumption when the system is idle. This new stepping will likely be used in other Pentium D's moving forward, as it offers similar performance at a lower TDP. Unfortunately, we don't have many details regarding the changes made with the new stepping, but we suspect some details will emerge in the coming days.
Intrigued by the fact that this processor is based on a totally new stepping of the Presler core, we spent some quality time overclocking the new Pentium Extreme Edition 965 to see what kind of clock speed headroom it had left. Because the Extreme Edition 965 has an unlocked multiplier and the Asus motherboard we used for testing has the ability to alter the processor's multiplier via the system BIOS, we overclocked the 965XE using a combination of FSB and multiplier tweaks.
By default, the Pentium Extreme Edition 965's multiplier is set to 14 with a 266MHz quad-pumped front side bus (effective speed of 1066MHz). To overclock the CPU we first bumped up our processor's core voltage to 1.35v and raised the multiplier until the test system was no longer stable. With the multiplier set to 16 and the CPU running at 4.25GHz, we had no trouble running any benchmarks and considered the system completely stable. With the multiplier set to 17 though, for a final clock speed over 4.5GHz, we experienced some instability. At this point we slowly increased the front side bus frequency and found our peak stable clock speed was 4.36GHz (16 x 272MHz), an increase of over 600MHz. We should mention that this was done with the stock cooler. With a more exotic cooling solution, we suspect higher clock speeds would certainly be attainable.
As you can see in the image above, the stock cooler seemed perfectly capable of keeping temperatures in check. When we looked at the 955XE, we witnessed overclocked temperatures in the 70oC+ range and idle temps over 50oC. With the Pentium Extreme Edition 965 though, idle temps hovered around a much more manageable 35oC, while overclocked temps peaked at 63oC.