Server Board Family Datasheet

Intel® S5000 Server Board Family Datasheet System BIOS
Revision 1.3
Intel order number D38960-006
53
3.4.1 FBDIMM Open and Closed Loop Thermal Throttling
Open-Loop Thermal Throttling (OLTT)
Throttling is a solution to cool the DIMMs by reducing memory traffic allowed on the memory
bus, which reduces power consumption and thermal output. With OLTT, the system throttles in
response to memory bandwidth demands instead of actual memory temperature. Since there is
no direct temperature feedback from the Fully Buffered DIMMs (FBD), the throttling behavior is
preset rather than conservatively based on the worst cooling conditions (i.e., high inlet
temperature and low fan speeds). Additionally, the fans that provide cooling to the memory
region is set to conservative settings as well (i.e., higher minimal fan speed). OLTT produces a
slightly louder system than CLTT because minimal fan speeds have to be set high enough to
support any FBDs in the worst memory cooling conditions.
Closed-Loop Thermal Throttling (CLTT)
CLTT works by throttling the FBDs response directly to memory temperature via thermal
sensors integrated on the advance memory buffer (AMB) of the FBD. This is the preferred
throttling method because this approach lowers limitations on both memory power and thermal
threshold, therefore minimizing throttling impact on memory performance. This reduces the
utilization of high fan speeds because CLTT does not have to accommodated for the worst
memory cooling conditions; with a higher thermal threshold, CLTT enables memory
performance to achieve optimal levels. If the thermal sensors do not function properly (i.e,
unable to retrieve memory temperature readings), the system can respond accordingly to
enable either OLTT or CLTT.
Note: CLTT is only supported starting for specific BIOS, BMC and FRUSDR versions. See the
Release Notes for information on the software stack that applies to your product(s).
3.4.2 Fan Speed Control
System fan speed is controlled by the Baseboard Management Controller (BMC) functions of
the ESB-2 chip. During normal system operation, the BMC will retrieve information from BIOS
and monitor several platform thermal sensors to determine the required fan speeds.
In order to provide the proper fan speed control for a given system configuration, the BMC must
have the appropriate platform data programmed. Platform configuration data is programmed
using the FRUSDR Utility during the system integration process, and by System BIOS during
run time.
3.4.2.1 System Configuration Using the FRUSDR Utility
The Field Replaceable Unit & Sensor Data Record Update Utility (FRUSDR utility) is a program
used to write platform specific configuration data to NVRAM on the server board. It allows the
User to select which supported chassis (Intel or Non-Intel) and platform chassis configuration is
being used. Based on the input provided, the FRUSDR writes sensor data specific to the
configuration to NVRAM for the BMC controller to read each time the system is powered on.
3.4.2.2 Fan Speed Control from BMC and BIOS Inputs
Using the data programmed to NVRAM by the FRUSDR utility, the BMC is configured to monitor
and control the appropriate platform sensors and system fans each time the system is powered
on. After power-on, the BMC uses additional data provided to it by System BIOS to determine
how the system fans should be controlled.