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The Power Saving Guide, Part 2

Test Results

RAM Speeds And Timings

Memory SpeedTimingsVoltageSystem Idle PowerMax. System Power
DDR2-5333-3-3-91.8 V148 W189 W
DDR2-5335-5-5-151.8 V148 W189 W
DDR2-6673-3-3-91.8 V149 W191 W
DDR2-6675-5-5-151.8 V149 W192 W
DDR2-8003-4-3-92.0 V152 W196 W
DDR2-8005-5-5-151.8 V151 W193 W
DDR2-10665-5-5-152.1 V158 W205 W

Using DDR2-1066 RAM increases the system power draw (and memory cost) considerably, without delivering a huge performance increase.

Graphics Cards

Graphics CardSystem Idle PowerMax. System Power
Nvidia GeForce 8800GTS143 W248 W
Nvidia GeForce 7800GT103 W184 W
Nvidia GeForce 6800GT117 W189 W

GeForce 7 can be considered the most efficient GeForce graphics card, as both its successor and its predecessor required more power. The latest GeForce 8 series is a power hog, which we cannot recommend for efficiency-aware users unless you want maximum performance or DirectX 10 support now.

Hard Drives

Hard DriveSpecsSetupSystem Idle Power
Western Digital WD1500ADFD (150 GB)3.5" - 10,000 RPM4 platters145 W
Seagate Barracuda ES (750 GB)3.5" - 7,200 RPM4 platters143 W
Samsung HD321KJ (320 GB)3.5" - 7,200 RPM2 platters141 W
Samsung HM160JI (160 GB)2.5" - 5,400 RPM2 platters134 W

The difference between a 10,000 RPM WD Raptor and other 7,200 RPM drives is only noteworthy when compared to hard drives with few platters (1-2). In other cases, the energy requirements will only differ by a few watts.

Add-On Cards

Add-On cardsSystem Idle Power
no add-on cards143 W
Intel Pro/1000 MT Network Card145 W
Adaptec 1430SA SATA RAID Controller148 W

Adding expansion cards increases the power requirements, but the two test cards (a network card and a storage controller) didn't boost consumption by much.