MacBook Pro 17-inch SMC Firmware Update (#2): Effects unclear

Earlier this week, Apple released an SMC (System Management Controller) firmware update for the MacBook Pro 17-inch. According to Apple, the update "adjusts fan behavior."

The ostensible reason for this update was to increase fan activity in an attempt to reduce excessive heat. However, reader reports are inconclusive regarding whether or not overall operating temperatures have been reduced.

MacFixIt reader Marc Marshall writes:

"I've installed the 17" MacBook Pro SMC Firmware Update (it didn't seem to show in my Software Update until after I had installed 10.4.7), and I can't say I've noticed any significant difference one way or the other.

"Both before and after, I can only hear the fan if the computer is under heavy load and playing a game, in which case the processor core tops out at a hair over 80C. This has not changed.

"I forgot do a side-by-side test to make sure, but it's possible it did decrease the processor core temperature at idle by about 5C; after the update it is consistently idling in the low 50s (usually 51C), and I'm *almost* positive that before at very low load (just typing, for example) it tended to idle in the high 50s. It's possible that my memory is faulty on this, however, and regardless, there's no noticeable increase in fan noise or activity--it is functionally silent. These are at a room temperature of about 25C, by the way, with good airflow underneath--it's on a wire 'mini-table'.

Another reader adds:

"My lap was burning under my 17" MacBook Pro. I installed the firmware, and it seemed better for a day, but now it's cooking again."

Finally, MacFixIt reader Don Richards adds:

"I  ran a before and after test for this firmware update on my MacBook 17" - processor load was Parallels running an AVG scan plus Quicktime playing a movie. In both runs the temperature topped out at around 83 degrees C. Verdict has to be that at that load there is no change in temperature control."

Feedback? Late-breakers@macfixit.com.

Previous coverage:

• MacBook Pro 17-inch SMC Firmware Update released

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