Dennis Forbes is a Toronto-based software architect. While focused primarily on the .NET and SQL Server worlds, Dennis frequently ventures outside of this comfort zone into game development and image processing. He has been published in several industry magazines, has been quoted in the Wall Street Journal and has been interviewed by NPR.
I've been thinking a lot about power consumption in our PCs. For instance that a PC sitting idle, monitor(s) in standby mode, is consuming 70W or more in many cases. All while doing nothing more than anxiously awaiting your return (if you're silly enough to run some sort of 3D "screensaver", that number increases significantly).
Often they're idling around the clock on the off chance that you might wander by and desire instant PC satisfaction. In the corporate setting it's frequently policy to leave workstations on around the clock, for the infrequent occasion that the network admin team needs to roll out a patch.
In the former case you should look at standby or "hibernation". In the latter case, the admins should be using Wake-on-LAN, which is supported close to universally. Dated arguments about system failure or hard drives seizures on start-up aren't rational, or even statistically valid worries.
Which brings me to online power consumption: the power your
computer is burning when it's busy doing actually useful
work for you. Over the past decade processor power consumption has
skyrocketed (with brief retreats, followed by the next surge
into power gluttony). Thankfully, though, the power consumed by a
processor does scale in a loose correlation with load: A processor
at 100% utilization uses more power, and generates more heat, than
one idling, courtesy of various power saving strategies available
on modern PCs and operating systems (such as the HLT instruction).
This is even more evident with mobile processors, which actually
reduce the voltage under a lower processing load, saving even more
energy (and thus reducing the heat output proportionately, as well
as the need for noisy internal fans).
These savings are offset, though, by the monster co-processor that most PCs have: The videocard GPU, which offloads 3D graphics operations to a hugely complex piece of silicon (video card GPUs are far more complex than your CPU in most cases). Couple that with huge amounts of power-sucking ultra-high speed onboard memory, and video cards are now pushing 150W+ of power consumption under a load (such as when running a 1st person shooter). Thankfully modern video subsystem turn off a substantial portion of their circuitry when it's unneeded, such as in the 2D world when composing a document in Word, vastly reducing power consumption.
Nonetheless when the demand is high and you add together the load of a processor running at 100% with a video card doing the same, you have a recipe for a tremendous power sink that doubles as a competent space heater.
The end result of this power consumption is increased resource usage, higher electric bills and demand on the grid, PCs that require more fans and cooling solutions (and thus create more noise pollution), and often a hotter, less comfortable environment.
Even if you don't care about the environment or rising power costs, and if you enjoy the balmy 40C room temperature, when you're using a mobile PC the the lifespan of your battery, along with the ability to use your laptop without it igniting your pants on fire, depends upon the efficient use of computing resources. In that case you absolutely want your processor and supporting systems (e.g. graphics GPU) doing the absolute least amount of work possible to satisfy your requirements, doing what matters to you without wasting cycles with frivolity.
Which brings me to Windows Vista (previously Windows Longhorn).
One of the major new features of Windows Vista is the Aero Glass experience (both as an API for applications, and the shell itself). Aero Glass in essence turns your desktop into a video game: Instead of the current model where the GDI draws on a 2D palette, updating the video card memory (making use of acceleration routines that the video card supports) only when changes occur, the model of Aero Glass is that of a traditional game: With every "frame" the scene is wiped clean and re-rendered from scratch, layering "textures" that represent application canvases onto 3-D polygons and building the user experience from there.
This system will attempt to push 60-90FPS of user experience goodness through your video card.
In many cases this will max out even high end video cards. Even where it doesn't, all of the shaders and T&L engines on the video card are engaged - the additional power consumption will be considerable. This could easily add 150W+ to your system power load, and could absolutely devastate battery lifespan for portables. This is on top of the fact that you're suddenly measuring your GUI in frames per second.
In other words the new, shiny user experience in Aero Glass isn't just making use of unleveraged hardware in your PC (which is a valid point - there's a big powerful graphics card there, so why should it go to waste) - It's also considerably adding to the power consumption, heat generation, and cooling requirements. In the mobile world it would be hugely detrimental to the battery lifespan.
All to add a bit of eye candy that, at least as far as I've seen, marginally improves usability.
