Margin Note: Why are three chimes recommended for a PRAM/NVRAM reset?

Yesterday we noted a possible fix for issues with sleep/shutdown behavior that involved resetting PRAM/NVRAM via a startup keyboard command that invokes flushing. As part of the fix, we noted that the appropriate keys (Command, Option, P and R) should be held immediately at startup. If you continue holding the keys, a second startup chime will occur, then a third, a fourth, and a fifth, etc, until you release the keys.

As part of the fix, we noted that the keys should be held until three startup chimes are heard. This runs contrary to Apple's advice, which suggests that only two chimes are necessary.

One MacFixIt reader inquired about the discrepancy, writing:

"What are you talking about a 3rd time. My G5 iSight iMac only chimes the second time ? indicating PRAM has been set. Please see Apple's Article ID 2238, it plainly states the 2nd time."

This reason for our recommendation is that we've personally experienced cases where holding for two chimes does not resolve issues where holding for three chimes does. Specifically, it was an issue where a MacBook Pro's battery was not being charged by the system. We're not sure if the fix worked because of different parameters being reset with the extra chime or not (it could have been that the problem required multiple PRAM resets and the three-chime procedure happened to be the right one), but there's no harm in holding for an extra chime.

Feedback? Late-breakers@macfixit.com.

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