Monday September 24, 2007

CPUs and Power Savings

Last week I went to San Francisco to have my fingerprints taken. The government office at 250 Broadway is a hole in the wall on the outside, and a remodeled warehouse on the inside, about 10000 sq ft. There are eight stations equipped with inkless fingerprint scanners, Samsung LCDs and what seem like generic PCs. Each finger is scanned at least once, its image appears on the screen and, before proceeding to next finger, the worker has to wait several seconds while the computer analyzes it.

My mind wandered about how much energy it takes to run an office like this and what role computers play in it. CPU vendors like to brag about performance per watt, but things might look different in the bigger scheme. In this case, if CPUs were to analyze images faster, the office performance measured in "people per day" would increase. Even if faster CPUs were more power-hungry, their contribution into the total office power consumption would be negligible.

Say, 50 watts per CPU increase is: 8 PCs * 50 W * 8 hours = 3200 Wh
30 * 50W fluorescent bulbs to light the office * 8 hours = 12000 Wh

Add air conditioning and you get the picture. The "people per watt" metric would still improve. Though this is hugely simplified, it illustrates the importance of the holistic approach.

Anyway, this silly stuff kept me occupied while waiting in line, in addition to reverse engineering fellow immigrants' life stories from their looks (and sometimes smells). As of last week, I'm in The System and, what, I have to wear gloves now? Darn.

(2007-09-24 16:20:38.0) Permalink