Intel X5365 Design Guide - Page 34

Figure 2-14. TCONTROL and Fan Speed Control Thermal/Mechanical Reference Design TCASEMAX TCASE@DTS= TCONTROL TCASEMAX@ P_PROFILE_MIN ② ① Thermal Profile TCASE Fan Speed Control Region P_PROFILE_MIN Power TDP Once the TCONTROL value is determined as explained earlier, the DTS temperature reading from the processor can be compared to this TCONTROL value. A fan speed control scheme can be implemented as described in Table 2-7 without compromising the long-term reliability of the processor. Table 2-7. Fan Speed Control, TCONTROL and DTS Relationship Condition FSC Scheme DTS≤ TCONTROL FSC can adjust fan speed to maintain DTS TCONTROL FSC should adjust fan speed to keep TCASE at or below the Thermal Profile specification (increased acoustic region). There are many different ways of implementing fan speed control, including FSC based on processor ambient temperature, FSC based on processor Digital Thermal Sensor (DTS) temperature or a combination of the two. If FSC is based only on the processor ambient temperature, low acoustic targets can be achieved under low ambient temperature conditions. However, the acoustics cannot be optimized based on the behavior of the processor temperature. If FSC is based only on the Digital Thermal Sensor, sustained temperatures above TCONTROL drives fans to maximum RPM. If FSC is based both on ambient and Digital Thermal Sensor, ambient temperature can be used to scale the fan RPM controlled by the Digital Thermal Sensor. This would result in an optimal acoustic performance. Regardless of which scheme is employed, system designers must ensure that the Thermal Profile specification is met when the processor Digital Thermal Sensor temperature exceeds the TCONTOL value for a given processor. 34 Quad-Core Intel® Xeon® Processor 5300 Series Thermal/Mechanical Design Guidelines (TMDG)