What do the letters after the processor speed mean?
Intel® Pentium® 4 processors that share the same core speed in GHz may have different product features. In cases where different processors exist at a single speed, letter designators are added to the processor core speed. Distinguishing features include the size of the L2 Advanced Transfer Cache, the speed of the front side bus, and the type of manufacturing process used.
This letter designator identifies Pentium 4 processors with 512KB full speed L2 Advanced Transfer Cache. For example, the Pentium 4 processor at 2 GHz has 256KB L2 cache while the Pentium 4 processor at 2A GHz has 512KB L2 cache.
This letter designator identifies Pentium 4 processors that support a 533 MHz front side bus speed. For example, the Pentium 4 processor at 2.40 GHz supports a 400 MHz bus speed and the Pentium 4 processor at 2.40B GHz supports a 533 MHz bus speed.
This letter designator identifies Pentium® 4 processors that support Hyper-Threading Technology and an 800 MHz front side bus. For example, the Pentium® 4 processor at 2.40C GHz supports an 800 MHz front side bus and Hyper-Threading Technology1.
||The letter 'D' is not used at this time.|
This letter designator identifies Pentium® 4 processors that are manufactured using the 90 nanometer process with 1MB L2 Advanced Transfer Cache.
One exception is the Pentium® 4 processor at 2.80A GHz. In this case the 'A' designator indicates a Pentium® 4 processor at 2.80 GHz with 1 MB L2 cache, 533Mhz front side bus built using 90 nanometer process. This processor does not support Hyper-Threading Technology1.
If no letter designator is present, then there is no overlap in process technology or front side bus speed at that processor core speed. For example, all Pentium 4 processors at 3.06 GHz are built using the 0.13 micron process technology and support a 533 MHz bus speed; therefore, no letter designator is indicated.
1Hyper-Threading Technology requires a computer system with an Intel® Pentium® 4 processor supporting HT Technology and a Hyper-Threading Technology enabled chipset, BIOS and operating system. Performance will vary depending on the specific hardware and software you use. See http://www.intel.com/info/hyperthreading/ for more information including details on which processors support HT Technology.
This applies to: