Technical Product Specification

Intel® Server Boards S4600LH2/T2 TPS
Revision 2.0
168
Option Values: Auto
DCLTT
SCLTT
SOLTT
Help Text:
Sets Thermal Throttling mode for memory, to control fans and DRAM power as needed to
control DIMM temperatures.
[Auto] – BIOS selects mode. BIOS automatically detect and identify the appropriate thermal
throttling mechanism based on DIMM type, airflow input, and DIMM sensor availability.
[DCLTT] – Dynamic Closed Loop Thermal Throttling.
[SCLTT] – Static Closed Loop Thermal Throttling.
[SOLTT] – Static Open Loop Thermal Throttling.
Comments: The Thermal Throttling Mode chosen reflects whether the DIMMs have
Temperature Sensors (TSOD), and whether the chassis is an Intel chassis for which thermal data are
available. Note that this is for thermal throttling only, independent of any controls imposed for the
purpose of power limiting.
The server board provides support for system thermal management through open loop throttling (OLTT)
and closed loop throttling (CLTT) of system memory. Normal system operation uses closed-loop
thermal throttling (CLTT) and DIMM temperature monitoring as major factors in overall thermal and
acoustics management. In the event that BIOS is unable to configure the system for CLTT, it defaults to
open-loop thermal throttling (OLTT). In the OLTT mode, it is assumed that the DIMM temperature
sensors are not available for fan speed control.
Throttling levels are changed dynamically to cap throttling based on memory and system thermal
conditions as determined by the system and DIMM power and thermal parameters. The BMC’s fan
speed control functionality is linked to the memory throttling mechanism used.
 DCLTT is the expected mode for a board in an Intel chassis with inlet and outlet air
temperature sensors and TSOD. The firmware can update the offset registers for closed
loop during runtime, as BIOS sends the dynamic CLTT offset temperature data.
 SCLTT would be used with an OEM chassis and DIMMs with TSOD. The firmware does not
change the offset registers for closed loop during runtime, although the Management Engine
can do so.
Both Static and Dynamic CLTT modes implement a Hybrid Closed Loop Thermal Throttling
mechanism whereby the Integrated Memory Controller estimates the DRAM temperature in
between actual reads of the memory thermal sensors.
 SOLTT is intended for a system with UDIMMs which do not have TSOD. The thermal control
registers are configured during POST, and the firmware does not change them.
Back to [System Acoustic and Performance Configuration]
1. Altitude
Option Values: 300m or less
301m-900m
901m-1500m
Higher than 1500m