If you have downloaded a new firmware update from Apple in the last month, you may have noticed something quite shocking: disappearing RAM. Whether you're one of the users whose RAM was disabled by the firmware download, or you're just interested in keeping tabs on the situation, here's what you need to know.
Apple released a firmware update on March 23 for nearly all of its machines--from iBooks to G4 towers. Apple said the update would "dramatically improve system stability and performance." Yet almost immediately, users began posting reports that once they had installed the update, it disabled their RAM. Some users with third-party RAM discovered that the Apple System Profiler couldn't find it anymore. For all practical purposes, it was as if the RAM just wasn't there.
After a week of user complaints, Apple commented on the firmware update. The company said that the update checks out users' RAM to make sure it meets Apple's specifications. "This check was added to help alleviate random crashes and stability issues," an Apple spokeswoman said. "The new memory test disables memory DIMMs that are found to be out of specification and DIMMs that cannot be determined to be compatible." (DIMM stands for Dual Inline Memory Module--it's a small circuit board filled with RAM chips.)
In other words, if your RAM doesn't meet Apple's specs--even if it worked without a hitch before--the firmware update will disable it. Apple added that it would be up to users and vendors to fix the problem.
Some RAM vendors responded with guarantees that their products would meet Apple's specs. Other vendors offered rebates or replacements for disabled RAM. But some users still found themselves out of luck with vendors who were unwilling to make replacements.
But one Mac developer, Glenn Anderson, chose to light a candle rather than curse the darkness and wrote a utility called DIMMCheck that makes sure that a user's RAM meets Apple's specs. The utility helps you ensure your RAM won't be disabled before running the firmware update. In addition, Anderson just released another application, DIMMFirstAid, that helps users regain their lost RAM.
The more typical response was to complain furiously about it on bulletin boards. As Macworld.com forum participant San Acoustic noted, Apple's firmware update was the equivalent of having someone "disabling the spark plugs in your car because they aren't gapped properly."
The bottom line: whatever you do, don't install any firmware updates until you make sure it won't disable your RAM, and stay tuned to Macworld.com and sister site MacCentral to keep abreast of the latest news.