New Laptop, Noisy Power Circuitry

After two years of wishing for a real delete key, I’ve finally sold my Powerbook G4 Aluminum and exchanged it for a brand new Lenovo Thinkpad X61s. I was seduced by the 17W TDP on the Core 2 Duo LV L7500 , excellent battery life and a very good promotional price. This laptop has turned out to be a very nice computer.

One troublesome feature (the only one thus far) of this laptop is high frequency noise, probably in the 19-21khz range whenever the processor is switching power modes. If I lock the CPU to one particular FSB/CPU speed the noise goes away. I’m certain that this is a combination of rapidly changing power requirements and cheep capacitors.

Many electronic devices I own emit high frequency noise associated with signaling or changes in power states. Am I exceptional in my ability to hear all this Chirping, Whining and Whisting? On some devices I can even distinguish HID device interrupts from bulk transfers to the video card. A saturated bus is also easy to pick out. While the ability to hear PCI bus traffic is instructive, it gets old really fast.

Read this paper to learn what cheap power circuitry can tell your enemies: Acoustic Cryptanalysis

New Laptop, Noisy Power Circuitry