User guide

User Guide CC8-BLUES • Multi-Processing CompactPCI CPU
- 20 -
EKF Elektronik GmbH • Philipp-Reis-Str. 4 • 59065 HAMM • Germany
Tel. [phone] • Fax. [phone] • E-Mail [e-mail] • Internet http://www.ekf.de
A special method to reduce power consumption is to force the processor into the 'Throttle
Mode'. This is achieved by actuating the 'Stop Clock' input of the CPU, and can be activated
through the BIOS settings. A Throttle Mode of 50% e.g. means a duty cycle of 50% on the stop
clock input. However, while saving considerable power consumption, the data throughput of
the processor is also reduced. The table below shows the effect of several throttle mode settings
on the processor temperature in a given system equipped with the CC8-BLUES. The CPU is a
850MHz Pentium-III processor, the airflow around the CC8 cards slot is about 16m
3
/h, which is
typical for EKF systems. While the testing procedure, the CPU is stressed to its maximum by
running kpower.exe.
Ambient
Temperature
o
C
Climate
Chamber
Throttle Mode (PIII-850)
o
C
0% (100% duty) 25% 50% 87.5%
Board Die Board Die Board Die Board Die
40 52 74 50 68 48 60 42 48
45 59 82 58 75 54 66 50 54
50 64 87 64 82 60 72 55 58
55 71 93 69 86 66 77 61 63
60 76 98 74 91 71 82 65 67
65 81 104 79 96 76 87 71 72
70 87 110 84 102 81 92 76 78
75 92 115 89 107 87 98 80 81
80 97 119 95 112 92 103 85 86
85 1) 1) 100 117 97 108 90 92
90 1) 1) 102 113 95 97
95 108 119 101 102
100 1) 1) 106 107
1) System not operational anymore
From the table on the previous page the maximum allowed die temperature of the PIII-850 can
be derived as 80
o
C. If a small amount of overtemperature would be tolerated, the test system
can be operated up to 45
o
C ambient temperature at 0% throttle mode, and up to 75
o
C at
87.5% throttle mode. However, the processor under test did remain fully functional up to
~120
o
C die temperature. Under typical conditions (not executing kpower.exe), the heat
dissipation of the CPU would be remarkable lower, thus increasing the maximum ambient
temperature of the CC8-BLUES.