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Corporate PC power consumption difficult to trim

More and more companies are eying their power bills and looking for ways to …

Green may be the new black of the advertising industry, but an increasingly large number of corporations are interested in cutting energy use to save both the planet and their pocketbooks. Rising fuel costs inevitably translate into rising energy costs, and while much of the US enjoys cheap power (7¢ per KwH in Louisville, KY, according to last month's bill), rates aren't exactly headed down. With no price relief expected in the near future, companies are searching for ways to cut their electricity use.

We've already seen an increasing number of organizations express concern over data center power consumption and cooling costs, but up to now, comparatively little has been said about desktop energy utilization. The power draw of a data center outweighs that of a desktop by orders of magnitude, but the scales begin to balance when you consider just how many desktops a given company might own. 

Ironically, tackling the problem of corporate desktop energy efficiency (or lack thereof) is both amazingly easy and mind-bogglingly complex. Low-hanging fruit, generally speaking, is everywhere, but the cost and difficulty of picking it can significantly complicate the situation—imagine an orchard full of delicious, succulent, ultra-nutritious and organic apples that explode when dropped, and you've got the idea. In this case, we'll consider the hardware angles first, while keeping a careful eye out for flying bits of fruit. 

Hardware support for low-power operation isn't usually the issue, at least, not in theory. Intel, AMD, and VIA all have their own methods of reducing processor speed and voltage when the system is under minimal load, and all three are fairly aggressive about it; the CPU's clockspeed will often start to drop after just 10-20s of idle time. Just what type of power reduction the user ends up with, however, depends on a number of factors. Some of the more advanced features of Intel's SpeedStep technology must be enabled and supported in BIOS, and many retail motherboard manufacturers ship their boards with features like C1E (an enhanced Intel halt state) disabled by default.

Enabling all the appropriate features in BIOS is not the end of the issue, at least not in Windows XP or Windows 2000. By default, these two operating systems use the "Home/Office Desk" power utilization profile, which disables SpeedStep, Cool'n'Quiet (AMD) and PowerSaver (VIA). Users must manually change the power scheme to "Minimal Power Management" to enable any of the three. Once that's done, the requisite CPU driver must be installed. VIA and AMD both offer such a driver themselves, while Intel insists that system (or motherboard) manufacturers provide SpeedStep support themselves. XP or 2K could be quickly reconfigured via a policy change, but adjusting BIOS settings and verifying that the changes took appropriately across the various PCs would inevitably take some hands-on work. 

Windows Vista actually makes the process easier, since there's no need to install additional CPU drivers, and the various power management options are enabled by default, but that OS is far from ubiquitous. Even if everything on the hardware front is in order, there are a number of other hurdles. The simplest way for a corporation to save power would be to shut its computers down every night, but that's often impossible. Many companies schedule I/O-intensive tasks for off hours, including data backup, disk defragmentation, and anti-virus scans. Certain servers and workstations, meanwhile, may need to be left on 24/7 to ensure round-the-clock data access for customers, or may have other computational tasks that run during these times.

It's theoretically possible to configure a system to sleep, wake up, perform its assigned tasks, and then return to sleep, but again, this introduces additional variables, and hence the potential for additional trouble. The S1 sleep state that older systems use, moreover, isn't a very effective sleep state at all, and power consumption actually remains fairly high. Windows XP supports S3 (Sleep) and S4 (Hibernate) but again, there's the potential of BIOS interference—if the BIOS is told to use S1 when the system is put to sleep, XP's S3 support is irrelevant. Most computers will happily fall asleep, but, much like people, may wake up grumpy. Peripheral hijinks after sleeping have gotten rarer over the years, but can still occur. Again, this is an area where Vista improves upon XP. Vista was designed for smoother transitions between its sleeping and waking state,and Microsoft created a Hybrid Sleep mode (new in Vista) that functions as a blend between S3 (Suspend to RAM) and S4 (Suspend to Disk).

Under Vista, power management can be set via a group policy (no such option in XP), and resume states were significantly shortened. Hardware support for sleep states has improved over the years, but Microsoft significantly improved how Vista handles power state transitions—additional details are available in Microsoft's presentation (PPT), or on the Windows Vista blog.

The fact that companies are moving to cut power consumption despite these problems is a sign that the market doesn't expect the cost of energy to go anywhere but up. The short-term costs of power-saving measures would far outweigh any short-term savings for most companies, particularly those using older hardware. Long-term savings, however, could be substantial. Not only do the computers themselves draw less power, but the cost of cooling the building also goes down since the amount of heat being generated drops substantially. For a person running just one system, the effect is negligible, for a company, it isn't. Pushing low-power systems and lower power consumption is going to require concerted effort on a variety of levels, but there's room for substantial improvement in this sector. Long-term, Vista adoption could help, but companies are going to have to actually use the power-saving features the OS provides in order to realize any improvement.

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