Knowledge Base

Article Summary:

This article contains information regarding why my Precision Workstation T5600 won't POST, boot, or recognize memory correctly after upgrading the memory.

Table of Contents:

1. Maximum Size of Memory Supported in the T5600
2. Memory Population Rules
3. Memory Speed Supported

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1.	Maximum Size of Memory Supported in the T5600

The maximum amount of memory the Precision T5600 can support depends on the processor configuration. The T5600 supports up to two processors and each processor supports 4 dedicated DIMM slots. On systems with a single processor, up to 64 GB of memory is supported with the 4 DIMM slots available. On systems with dual processors, up to 128 GB of memory is supported with all 8 DIMM slots available.

The following chart provides supported memory population configurations. For a two-processor configuration, the processors will be labeled CPU 0 and CPU 1, respectively.






The version of Windows installed on the T5600 will also affect the amount of memory the operating system can recognize. 32-bit versions of Windows will only recognize a maximum of 4 GB of memory, and there are further limitations with some 64-bit versions of Windows. Check the memory limits for the different versions of Windows before attempting to upgrade the system memory.

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2.	Memory Population Rules

The memory controller on the T5600 supports dual-channel, triple-channel, and quadruple-channel architectures. The memory DIMMs within a specific channel must be populated starting with the DIMMs farthest from the CPU. The DIMM slots 1, 2, 3, and 4 must be populated before slots 5, 6, 7, and 8.

To ensure maximum channel performance, memory modules should always be installed in pairs of matched size, speed, and technology. The system will operate with reduced memory performance whenever mis-matched pairs of memory are installed.

For example, to achieve quadruple channel performance a multiple of four memory modules identical in speed and capacity need to be installed in quad-channel slots. When only two memory modules are installed in these slots, the system memory performance will revert to dual-channel mode. When only three memory modules are installed, the system memory performance will operate in triple-channel mode.

Follow the link for more detailed information concerning multi-channel memory architecture.

The picture below shows how the memory slots are situated on the motherboard and with respect to the CPU:



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3.	Memory Speeds Supported

The T5600 supports DDR3 unbuffered or registered ECC SDRAM modules with speeds of 1333MHZ and 1600MHZ. DDR3 memory provides a boost in access speed, and also allows for individual chip capacities up to 8 GB on each memory module. A motherboard which supports DDR3 can only support this memory type as it is keyed differently than previous memory modules:



When memory modules of different speeds are installed, all DIMMs will operate at the speed of the slowest installed DIMM. For example, if the system includes a mixed configuration of 1333MHZ and 1600MHZ memory modules, the overall system memory access speed will be 1333MHZ.

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