Intel Core 2 Extreme QX9650, formerly known as Yorkfield, is the first 45-nm desktop CPU from Intel, being a quad-core CPU running internally at 3 GHz and externally at 1,333 MHz, the same clock specs of Core 2 Extreme QX6850. QX9650, however, brings two novelties: the new SSE4 instruction set and a larger 12 MB L2 memory cache, making it the most high-end desktop CPU available today. Did these two new features improve the CPU performance? That is exactly we are going to find out.

Intel Core 2 Extreme QX9650Figure 1: Core 2 Extreme QX9650 engineering sample.

We have already written two articles explaining what is new on the 45 nm manufacturing technology from Intel, also known by the codename Penryn: Details on Intel’s Forthcoming 45 nm Manufacturing Technology and Penryn Core New Features. We highly recommend you to read these two articles in order to understand the manufacturing technology behind Core 2 Extreme QX9650.

Just to clarify, Penryn isn’t the codename of a specific processor, but the codename of Intel’s 45-nm manufacturing process. The codename for desktop CPUs using Penryn technology is Yorkfield. So you might see this CPU being referred by these two codenames.

In the table below we summarized all CPUs included in this review with their main specs. As we mentioned Core 2 Extreme QX9650 has exactly the same clock specs as Core 2 Extreme QX6850 – working internally at 3 GHz, which is obtained by multiplying its external clock by 9 – so we were very curious in comparing these two CPUs.

As you can see, this quad-core CPU continues to use two L2 caches, so its 12 MB L2 cache is in fact two 6 MB caches, the first one being shared between cores 1 & 2 and the second one being shared between cores 3 & 4. For a more detailed explanation on this subject please read our article Intel Quad-Core CPU Overview and Roadmap.

For the record, we always configured our DDR2-1066/PC2-8500 memories running at 1,066 MHz.

CPU Cores Internal Clock External Clock L2 Memory Cache SSE4 Platform TDP Man. Tech.
Core 2 Extreme QX9650 4 3 GHz 1,333 MHz (333 MHz x 4) 6 MB x 2 Yes Socket LGA775 130 W 45 nm
Core 2 Extreme QX6850 4 3 GHz 1,333 MHz (333 MHz x 4) 4 MB x 2 No Socket LGA775 130 W 65 nm
Core 2 Extreme QX6700 4 2.66 GHz 1,066 MHz (266 MHz x 4) 4 MB x 2 No Socket LGA775 130 W 65 nm
Core 2 Extreme X6800 2 2.93 GHz 1,066 MHz (266 MHz x 4) 4 MB No Socket LGA775 75 W 65 nm
Core 2 Duo E6750 2 2.66 GHz 1,333 MHz (333 MHz x 4) 4 MB No Socket LGA775 65 W 65 nm
Core 2 Duo E6700 2 2.66 GHz 1,066 MHz (266 MHz x 4) 4 MB No Socket LGA775 65 W 65 nm
Pentium 4 550 1 3.4 GHz 800 MHz (200 MHz x 4) 1 MB No Socket LGA775 115 W 90 nm

TDP, Thermal Design Power, is how much power the CPU dissipates, meaning that you must match the CPU with a cooler capable of dissipating that amount of power.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.