Wednesday, August 31, 2005

Within a few months, we began to suspect a problem as, one by one, Popular Mechanics's new iMac G5s started to overheat and then die. Eventually, 40 percent of them had to be sent back to Apple for repair or replacement. When we looked into the problem, we found a number of complaints about overheating power supplies and "bloated," apparently heat-damaged, capacitors on the midplane circuit board. These were posted on Apple's own online user forum as well as user groups such as MacOSG, TidBITS and MacInTouch.

Complaints became so numerous that MacInTouch recently conducted its own reliability survey of iMac G5 owners. Of 1948 responses, the site's survey found there was an 18 percent failure rate among the original iMac G5 machines with 17-in. screens, and a troubling 31 percent failure rate for models with a 20-in. screen. (Recently purchased models had far lower failure rates--of around 11 to 12 percent.)

To investigate further, we sought out the services of heat-imaging company Electrophysics. The company brought in a $100,000 thermographic camera. Surface thermographic images of an original iMac G5 with the back cover removed revealed heat buildup around the hard drive and processor, and surrounding the capacitors on the midplane board.