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Computers generate a great deal of waste heat. Active cooling is the most popular method of venting heat, by using powered fans that move air through the computer. However, because a powered fan gets electricity from the systemboard and the computer’s power supply, the fan must spin fast enough to transfer any heat that the fan motor generate, as well as the waste heat the fan is supposed to divert from the CPU and other computer parts. Powered fans also increase the electricity requirements of a computer.

Residential users are more likely to be annoyed by fan noise than energy costs. Media center computers often use fast processors, high-end graphics cards and large hard drives to drive large video screens. Audiophiles do not want fan noise to ruin their experience, so these computers are often designed to reduce fan noise.

In a data center or a server room, the noise generated by hundreds of fans can reach 85 dB (decibels) and louder. That’s loud enough to trigger OSHA regulations, so some data centers provide noise canceling headphones or earplugs for their personnel. As data centers become larger, with faster computers that have louder fans, data centers are now using noise insulation, liquid cooling, and other technologies to manage their physical environment. A few data centers are using low power computers that produce less heat and fan noise. See this 31 July 2007 article from ComputerWorld for more details.

In some computers, passive or convection cooling is a key design element. Apple’s laptops and the Mac Mini have small fans that provide active cooling. In fact, small fans are used in many laptops and small form factor (SFF) desktop computers. As I mentioned in my 3 March 2008 post, laptop designers have to with tightly integrated components. There is much less airspace inside a laptop case than in a desktop computer case.

Passive cooling is also used in many laptop and SFF computers to reduce electrical power consumption. Heat is diverted by connecting the systemboard to the computer case, while small vents allow cool air to enter the computer case. The computer components warm and expand the air inside the case, pushing the heated air out of the case while drawing cool air inside. This article at PowerBook Central provides a nice discussion.

Some laptop owners have noticed that underside of their computers becomes very warm during use. Many laptop computers have vents on their underside. Laying the laptop flat against a table will block the vents, and cause hat to build up inside the computer. Some laptop computers can become too warm to be placed on a user’s lap. I use a plastic or metal stand to raise the computer off the table or away from my lap. I haven’t tried a USB-powered stand, which plugs into a laptop computer’s USB port to spin small fans in the stand. The fans provide active cooling, drawing heat away from the computer case and pulling air through the computer’s vents.

A Stirling idea

TweakTown (via BoingBoing Gadgets) has an article about a clever cooling system that harnesses waste heat to provide active cooling without drawing electricity. MSI has devised a fan motor that is powered by a small Stirling engine, which uses waste heat to power the fan. The system is very quiet. HowStuffWorks and Wikipedia each have articles about Stirling engines. There are several companies that design and sell Stirling engines. American Stirling Company sells small motors that are used as demonstration models. Swedish company Kockums has designed and launched 8 submarines equipped with large Stirling engines.

TweakTown also provided an MSI animation of this motor. I hope the real component moves faster than the simulation!

From BoingBoing comes the most disturbing information security news I have read in a while.

We’ve long assumed that disk encryption is a robust means of storing confidential data on a computer. Disk encryption products work by encrypting all of the data on a drive, including documents, the operating system, swap files and caches. Disk encryption software can start up before the operating system to let the user enter their password or key. Disk encryption software can also be used on USB storage, as well as partitions on an unencrypted drive.

Disk encryption helps travelers keep their data confidential. My post of 5 Janaury 2008 addresses how cryptography works.

Warm RAM, lost key

Princeton University researchers have developed a simple attack that can retrieve the BitLocker disk encryption key from a Windows Vista computer. The user has to have logged into the computer so that the encryption key is then stored in the computer’s RAM. If the computer is in sleep mode, running a screen saver, or still warm, the encryption key can be extracted from RAM. The extracted data can be saved to a USB storage device, so that another computer can take its time to analyze and fix any errors in the extracted key.

The same kind of attack will also work on Apple FileVault, TrueCrypt, PGP Whole Disk Encryption, and other disk encryption products. The research report is available as a PDF file at this web site.

Declan McCullagh has posted his analysis of the report at news.com. he points out that this vulnerability has been used by other researchers to pull data through a FireWire connection to an iPod. It is difficult to harden a computer against this form of attack, but the attack must be carried out in person. It cannot be done across the Internet, at least in the form that the researchers demonstrate. The attacker needs a USB drive preloaded with the attack software. A can of Dust-Off might also be helpful, to chill the RAM.

Watch that drive

The easiest way to harden a computer against this attack is to maintain physical control of the encrypted drive. Don’t leave it alone. Update the encryption software regularly, as the software developers will more than likely develop their own patches to wipe the key from RAM.
This YouTube video produced by the research team is a brief overview of the vulnerability and the attack.

Courtesy of BoingBoing, here’s a photo of at least five different electrical outlets that are available at each seat in a European conference room.

It’s not just the power outlets that are different. The outlets provide different voltages and frequencies of alternating current (AC), depending upon the standards. This Wikipedia article has a good discussion that I used to develop a key for the above photo. Going from left to right:

1. Type G or BS 1363: 240v, 50 hZ. Used in the UK, Singapore and South Africa
2. Type E: 220v, 50 hZ. Used in France, Slovakia, the Czech Republic, Denmark, and other European countries.
3. I have no idea what standard the third plug uses.
4. Type J or SEV 1011: 250v, 50 hZ. A Swiss model.
5. Type B, NEMA, PBG: 120v, 60 hZ. The standard 3-pin plug used in the US and Canada. Japanese plugs look similar, but use 100v and 50 hZ.
6. Again, I have no clue which plug this might be.

Every couple of months, someone asks me about a power issue. It might be electric plugs, battery life or power adapters. International travelers sometimes learn a hard lesson about voltage. If an outlet supplies too little voltage, the device will not work well or at all. This is a common issue for European visitors to Hawaii, as our 120v outlets provide only half the power that a European device might need it.

If the outlet provides too much voltage, the device might start smoking or burning. American visitors to Europe sometimes encounter this issue when they force a 12ov Type B plug into a 220v or higher European outlet.

I’ve long thought that the standard USB type A connector might become a standard electrical connector for low-power devices. USB usually provides only 5v of direct current (DC) at 100 or 500 milliamperes. That’s either 1 or 2.5 watts, so USB only useful for charging or running small devices.

DC is the common standard for batteries, and is also used inside almost every electronic device. Batteries have a limited lifespan, even when recharged.

But USB is an international standard, so more and more digital cameras, mobile phones and small devices use this interface for charging. Better yet, perhaps some company will start offering USB power outlets that can be installed directly into a wall.

Vendors have been selling inexpensive personal computers for years. Dell has offered models that are more-or-less disposable – the case is sealed, and the repair costs may exceed the computer’s actual value.

Business Week reported on 9 October that sales of ultra-low cost PCs are growing, especially in Asia and Latin America. One popular market for these computers is in schools, where students need durable computers. Some models lack hard drives, relying on flash memory and network storage instead. This 16 June 2006 ZDNet article describes an Intel project to design similar computers. The article also points out some of the distribution challenges in these markets. Weekly payments, microloans, content filtering and asset control systems are important features.

The One Laptop Per Child initiative provides similar computers that run the Linux operating system instead of Microsoft Windows. This 4 October article in the New York Times provides a brief overview of the XO project, and Laptop Magazine has an extensive hands-on review. Wikipedia has an article, of course, and it notes that Intel has redirected its ultra low-cost PC program to support the XO project.

As this spec sheet shows, the XO computer is not a fast device. Its power usage is only 2 watts, which is less than some PDAs and smartphones. The XO’s battery can be recharged in several clever ways, as described in this list from OLPC News.

Ultra-low cost PCs aren’t supposed to compete with standard consumer and corporate models, so the key success factors in this industry may become quite different than those found in mainstream PC markets. The XO is inexpensive, easy to manufacture, and easy to deploy in local schools.