Noise levels
Noise levels were measured with an Extech 407727 Digital Sound Level meter 1" from the side of the drives at idle and under an HD Tach seek load. Drives were run with the PCB facing up.
Our SSDs register 42.6 decibels here because that's the ambient noise level of the rest of the system from only 1" away. The drives themselves are completely silent. Mechanical drives are not, however, and spindle speed proves to be the determining factor at idle. Under a seek load, the Scorpios prove quieter than both Momentus drives, likely thanks to their use of Western Digital's IntelliSeek just-in-time actuator delivery mechanism, which allows the drive head to move less violently and yet still arrive in time for the next data point. Only a fraction of a decibel separates the mechanical drives' seek noise levels, though, so they're all pretty close.
Power consumption
For our power consumption tests, we measured the voltage drop across a 0.1-ohm resistor placed in line with the 5V line (mobile drives don't draw power from the 12V line) connected to each drive. Through the magic of Ohm's Law, we were able to calculate the power draw from each voltage rail and add them together for the total power draw of the drive.
Power consumption is an important consideration for notebooks, and SSDs prove their worth yet again. Well, the OCZ and Samsung drives do, anyway. Both register significantly lower power draw than our mechanical drives at idle and while seeking. The MasterDrive's seek power consumption is also lower than that of the mechanical drives, but it draws about the same amount of power at idle.
On the mechanical front, Seagate looks to have an edge at both 5,400 and 7,200RPM. What's interesting, though, is that the 7,200-RPM drives from both camps draw less power under load than their 5,400-RPM cousins.
To put things into perspective, the average laptop draws somewhere around 15W at idle. The small differences in power draw between mechanical drives aren't likely to translate to significant longer run times, but dropping in a SATA II or FlashSSD will probably buy you a noticeable boost in battery life
