Intel C2518 FH8065501516710 Data Sheet

Intel

®

 Atom™ Processor C2000 Product Family for Microserver

September 2014

Datasheet, Vol. 2 of 3

Order Number: 330061-002US

151

Two mechanisms for managing memory temperatures are available: the memory 

bandwidth counter and the memory module temperature monitoring. Since the SoC 

has no mechanism to determine the temperature of the memory modules, the BMC, or 

other platform-board external circuitry, is needed to provide this information via PECI 

over the SMBus. 

Memory event based bandwidth throttling is available as a fallback thermal protection 

feature if external thermal sensors are not available. Memory reads and writes are 

counted and compared to a threshold trip point to reduce memory bandwidth when 

needed to reduce memory module temperatures. These counter-based trip points are 

enabled using the thermal management control registers.

Open Loop Thermal Throttling (OLTT) and Closed Loop Thermal Throttling (CLTT) pass-

through is supported on the SoC to help optimize platform power/acoustics. The SoC 

supports DDR3 DRAM technology. The temperature sensor on DIMM (TSOD) is required 

for CLTT. OLTT is also supported. The

 

implementations of memory thermal throttling 

are defined as follows:

1. Open Loop Thermal Throttling: The system does not change any of the control 

registers in the memory controller during runtime. OLTT control registers are 

configured by BIOS MRC and remain fixed after post.

2. Closed Loop Thermal Throttling (pass-through): The system does not change any 

of the control registers in the memory controller during runtime. CLTT pass-through 

control registers are configured by BIOS MRC and firmware and remain fixed after 

post. The memory controller does not poll the DIMMs directly, so this mode still 

requires PECI over SMBus pass-through mode as described below.
a. PECI over SMBus pass-through: There is a PCU pass-through feature in which 

the BMC or other external controller can write temperature data to the PCU using 

PECI for platforms where the TSOD is not available.

b. The following temperature ranges are defined for the CLTT pass-through 

Memory throttling:

— 82 °C - Unconstrained performance, set throttling to peak.
— 93 °C - Set throttling to 10% of peak.
— 100 °C - Set throttling to 1% of peak to attempt to prevent system shutdown.