Power Consumption - Congatec COM Express conga-B915 User Manual

1.5

Power Consumption

The power consumption values listed in this document were measured under a controlled environment. The hardware used includes a conga-B915
module, conga-CEVAL and conga-Cdebug carrier boards, CRT monitor, SATA drive, and USB keyboard. When using the conga-Cdebug, the
SATA drive was powered externally by an ATX power supply so that it does not influence the power consumption value that is measured for
the module. The USB keyboard was detached once the module was configured within the OS. The module was first inserted into the conga-
Cdebug, which was powered by a Direct Current (DC) power supply set to output 12V. The current consumption value displayed by the DC
power supply's readout is the value that is recorded as the power consumption measurement for Desktop Idle, 100% Workload and Standby
modes. The power consumption of the conga-Cdebug (without module attached) was measured and this value was later subtracted from the
overall power consumption value measured when the module and all peripherals were connected. All recorded values are approximate.
The conga-Cdebug does not provide 5V Standby power therefore S3 mode was measured using the conga-CEVAL powered by an ATX power
supply with a multimeter attached to the 5V Standby power line. The 5V Standby power consumption of the conga-CEVAL (without module
attached) and all peripherals connected was first measured and the resulting value was later subtracted from the overall S3 power consumption
value measured when the module was attached. All S3 recorded values are approximate.
Each module was measured while running Windows XP Professional with SP2 (service pack 2) and the "Power Scheme" was set to "Portable/
Laptop". This setting ensures that Core 2 Duo and Core Duo processors run in LFM (lowest frequency mode) with minimal core voltage during
desktop idle. Celeron M processors do not support this feature and therefore always run at the same core voltage even during desktop idle.
Each module was tested while using a swissbit
memory modules, will cause slight variances in the measured results.
Power consumption values were recorded during the following stages:
Windows XP Professional SP2
• Desktop Idle
• 100% CPU workload (see note below)
• Windows XP Professional Standby Mode (requires setup node "Suspend Mode" in the BIOS to be configured to S1 POS (Power On
Suspend))
• Suspend to RAM (requires setup node "Suspend Mode" in BIOS to be configured to S3 STR (suspend to RAM)). Supply power for S3 mode
is 5V.
Note
A software tool was used to stress the CPU to 100% workload.
Copyright © 2008 congatec AG
DDR2 PC2-4200-444 512MB memory module. Using different sizes of RAM, as well as two
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