Intel is giving some existing 32 nm "Clarkdale" based Core i3 and Core i5 processors an update. The processors will transition to the new K0 stepping from the existing C2 stepping. The parts that will be made on the K0 silicon are Core i3 models 530 (new sSPEC: SLBX7), 540 (new sSPEC: SLBTD) and Core i5 models 650 (new sSPEC: SLBTJ), 660/661 (SLBTK/SLBTB), 670 (SLBTL). Newer and upcoming models such as the i3-550, i3-560, i5-665K, and i5-680 are already being built on the K0 stepping die. Motherboards will require a BIOS update to support the new K0 stepping processors.

The K0 stepping change includes the following highlights:

• New S-spec and MM numbers for the converting products
• Extended CPUID will change from 0x00020652 to 0x00020655
• Host RevID will change from 0x12 to 0x18
• K0 stepping package is pin compatible with C2 stepping package
• Adds Processor Context ID (PCID) support

The revised older SKUs that are built on K0 stepping will be market-available by October 16.