-written by Paul Henke, Dataram Memory Blog Team Member
DDR3-1333 is today’s mainstream memory speed and is the fastest memory supported in today’s best selling x86 2-way servers with Intel processors. However, many users are purchasing these servers and selecting Xeon processors that do not support this top speed grade of memory. Unfortunately, they are not aware their CPU selection will result in DDR3-1333 memory being clocked down to DDR3-1066 or an even the lowest memory speed, DDR3-800.
To make matters worse, some users are assuming the memory is not working correctly! After all, the DIMMs are marked as PC3-10600 (DDR3-1333). They conclude the memory must be the issue because a slower speed is being displayed upon booting up. To run at maximum speed, these DIMMs must be mated to a Xeon CPU that has the fastest QPI (Quick Path Interconnect) speed of 6.4 GT/s. In Intel‘s model number scheme, you must select a model number of 5650 or higher (up to 5698) to run at -1333. CPUs of model #5640 or lower, have a slower QPI speed, and cannot run DIMMs at DDR3-1333 memory speed.
Since DRAM manufacturers are currently yielding die that almost all are testing out at DDR3-1333 speed or higher, there is no price premium for selecting fast DDR3-1333 DIMMs. At Dataram we encourage users to select the faster memory, since there is no additional cost in doing so. If you have existing slower Xeon CPUs that results in slower memory operation, perhaps a CPU upgrade might be in your future, and you will already be set with the faster memory needed! Or you may need additional new servers and migrate your previously purchased Dataram DDR3-1333 DIMMs into one that does support this speed. In either case, memory is power, and the single best additive to make your applications run faster! Dataram has you covered with a complete line of server memory.