Power Consumption Tests
We decided to carry out a few practical tests to estimate how economical the new AMD Energy Efficient processors are. Therefore we compared the current power level in platforms equipped with different processors. We measured the currents going through the processor voltage regulator circuitry (this way we could check the processor power consumption without the processor voltage regulator efficiency) as well as through the entire system. As a result, we will be talking about two parameters: CPU power consumption and platform power consumption.
For our tests we used the following processors: regular AMD Athlon 64 X2 4600+ with 85W TDP, Energy Efficient AMD Athlon 64 X2 4600+ with 65W TDP and Energy Efficient AMD Athlon 64 X2 3800+ with 35W TDP. Our test platform was built using ASUS M2N32-SLI Deluxe mainboard based on Nvidia nForce 590 SLI chipset, 1GB DDR2-800 SDRAM, PowerColor X1900 XTX 512MB graphics card and Western Digital Raptor WR740GD HDD. The processor was cooled down by Zalman CNPS9500 AM2 air cooler.
To compare the obtained results against the power consumption of the competitor’s solutions, we measured the same parameters in the platform built with the new Intel processor on Core microarchitecture. The alternative competitor solution was built around Intel Core 2 Duo E6300 processor, which performance is almost the same as that of AMD Athlon 64 X2 4600+, and ASUS P5W DH Deluxe mainboard on Intel 975X chipset. The system was also equipped with the same graphics card, memory and hard disk drive. The CPU was cooled down with a similar air cooling solution from Zalman – CNPS9500 LED.
We measured the systems power consumption in different modes: in idle mode, during WMV video-movie playback from the hard disk drive, in a popular 3D benchmark – 3DMark06 and under maximum CPU and memory workload created by a special S&M utility.
So, first of all we measured the power consumption in idle mode with Cool’n’Quiet and Enhanced Intel SpeedStep activated.
In idle mode and with all CPU power-saving technologies enabled, AMD processors consume less power than the youngest Intel Core 2 Duo processor model. It may be determined by the fact that Cool’n’Quiet technology allows Athlon 64 X2 to drop the clock speed to 1.0GHz in idle mode, while Enhanced Intel SpeedStep lets Core 2 Duo drop its clock speed to only 1.6GHz.
If we disable the Cool’n’Quiet and EIST technologies, the situation gets slightly different:
The power consumption of AMD processors with 85W TDP gets much higher and they start eating up more power than their Intel rival, which power consumption increases just a little bit thanks to the Enhanced Halt State (C1E). As you remember from our previous articles, C1E technology just like EIST allows the CPU to drop its clock speed on Halt command from the OS. That is why Intel processor consumes so little power in this test.