Справочник Пользователя для Intel Server Board S5500HCV S5500HCVR

In the Independent Channel mode, you can populate multiple channels on any channel in any 
order. The Independent Channel mode provides less RAS capability but better DIMM isolation 
in case of errors. Moreover, it allows the best interleave mode possible and thereby increases 
performance and thermal characteristics.  

Adjacent slots on a DDR3 Channel from the Intel

®

 Xeon

®

 Processor 5500 series do not need 

matching size and organization in independent channel mode. However, the speed of the 
channel is configured to the maximum common speed of the DIMMs. 

The Single Channel mode is established using the Independent Channel mode by populating 
the DIMM slots from Channel A. 

The Mirrored Channel mode is a RAS feature in which two identical images of memory channel 
data are maintained, providing maximum redundancy. On the Intel

®

 Xeon

®

 Processor 5500 

series based Intel

®

 server boards, the mirroring is achieved across channels. Active channels 

hold the primary image and the other channels hold the secondary image of the system 
memory. The integrated memory controller in the Intel

®

 Xeon

®

 Processor 5500 series alternates 

between both channels for read transactions. Write transactions are issued to both channels 
under normal circumstances. The mirrored image is a redundant copy of the primary image; 
therefore, the system can continue to operate despite the presence of sporadic uncorrectable 
errors, resulting in 100% data recovery. 

In Mirrored Channel mode, channel A (or D) and channel B (or E) function as the mirrors, while 
Channel C (or F) is unused. The effective system memory is reduced by at least one-half. For 
example, if the system is operating in the Mirrored Channel mode and the total size of the DDR3 
DIMMs is 2 GB, then the effective memory size is 1 GB because half of the DDR3 DIMMs are 
the secondary images. 

If Channel C (or F) is populated, the BIOS will disable the Mirrored Channel mode. This is 
because the BIOS always gives preference to the maximization of memory capacity over 
memory RAS because RAS is an enhanced feature. 

The BIOS provides a setup option to enable mirroring if the current DIMM population is valid for 
the Mirrored Channel mode of operation. When memory mirroring is enabled, the BIOS 
attempts to configure the memory system accordingly. If the BIOS finds the DIMM population is 
not suitable for mirroring, it falls back to the default Independent Channel mode with maximum 
interleaved memory.  

Populating and upgrading the system memory requires careful positioning of the DDR3 DIMMs 
based on the following factors: 



 

Current RAS mode of operation 



 

Existing DDR3 DIMM population 



 

DDR3 DIMM characteristics