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Article Summary:This article provides information on "Processor Bus Speeds explained". Table of Contents: What is processor bus speed & how is it determined Examples of processor bus speed computation 1. What is processor bus speed & how is it determined The bus speed on Precision systems is based on 2 factors: Processor RAMUsing the Precision Workstation T5500 as an example. This system offers the Xeon E55XX class processor (Nehelem) in single or dual configurations. These are all quad core except the E5502. The processor chosen will determine the front side bus speed.When choosing a processor for systems on www.dell.com, there is a "Help me choose" link. You can use this tool to help you understand the choices available in the system you are reviewing. Back to Top 2. Examples of processor bus speed computation Using a Xeon E5506 as an example, it has a front side bus (FSB) ratio of 4.8. The standard clock multiplier for these systems is 166.67 Megahertz (MHz). When you multiply the two, you should come up with 800.16, so 4.8 x 166.67=800MHz which is what will show for Memory speed in the system BIOS for this processor.The Xeon E5550. It has a FSB rating of 6.4. 6.4 multiplied by 166.67 equals a bus speed of 1066.688, or 1066MHz.Here is a partial list of XEON E series processors: ModelSpeed (GHz)L3 Cache (MB)QPI speed (GT/s)DDR3 Clock (MHz)TDP (W) CoresThreadsTurbo-BoostW36803.33126.41333130612YL56091.86124.810664044NL56181.86125.8610664048YL56302.13125.8610664048YE56202.40125.8610668048YE56302.53125.8610668048YE56402.66125.8610669548YX56673.06126.413339548YX56773.46126.4133313048YL56382.00125.86133360612YL56402.26125.86133360612YE56452.40125.86133380612YX56502.66126.4133395612YX56602.80126.4133395612YX56702.93126.4133395612YX56803.33126.41333130612y RAM will also affect the bus speed by ranking and amount of RAM. The Precision T5500 uses 1066 MHz and 1333Mhz DDR3 un-buffered or registered ECC SDRAM memory. There are rules for how the memory is placed, but there is also the amount and rank of RAM that can factor bus speed. Even with the E5570 Xeon, if you max out the using quad ranked RAM in risers, the bus speed is most likely going to drop.Back to Top Click the button below to Tweet feedback or request assistance on anything in the above article.

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