In an effort to keep the latest Intel Macs super quiet, Apple did some great things to see heat dissipated by methods beyond just loud, fast spinning fans. Even so, with a heavy processing load there's definitely a point where having those fans crank up is a good thing. What's not so hot... ok... actually is literally a hot issue has to do with Apple's default thresholds for when the system will crank up its fans.
In the case of Apple's flagship Mac Pro, things can get mighty toasty in spots without some of the fans accelerating at all. One easy to recreate scenario is with any Mac Pro equipped with a Radeon 1900XT and the game World of Warcraft. With multiple reports all over the web, we've tested it ourselves to see our Mac Pro video go all wiggy with artifacts, have total system lock ups, and in one test experience a total loss of video with this game being played. Was it a bad video card? No - it was a big rise of temperature within that caused these problems.
How about those MacBook Pros - some people report having their MacBooks turning into 'MacCooks'. It's not your typical web browsing, e-mail reading, word processing, etc - that cranks up the heat - it's when you dive in with applications or even some games that use the system capabilities to their max. You don't break a sweat walking, but when you're running as fast as you can - you know. And these Macs are designed to run all out, but maybe there is a question to where Apple has the fans set to crank on.
And there is a solution. It's called smcFan Control. This application lets you set new minimum fan speeds for each fan your Intel Mac has. It's smart too... so you're not able to accidentally cook your Mac, minimum speeds are maintained and Apple's automatic fan speed increases will occur should your settings be lower than what Apple would automatically engage for a various load. What's particularly useful is that you can have multiple fan setting profiles to switch between for a particular situation. While you can leave the default Apple settings for the stuff that doesn't fire up the grill, a simple menubar pull down lets you select a custom fan speed profile to keep the heat off during an activity that does.
In the case of our World of Warcraft testing - we found that our PCI Expansion bay temp rose from around 90F to over 110F with problems starting after temps in the 105F+ range were registering. The room tested in was about 76F and when we cranked the fans from a default of about 700RPM to 1800RPM - the same load only brought the bay up to 94F and NO PROBLEMS AT ALL. A future Apple SMC update may very well have those fans bumping up automatically - until then, smcFan Control puts your Intel Macs temperature(s) in your hands with easy to use profiles so you'll only need to crank up the fans when you're cranking those apps you've seen crank the heat. Enjoy and don't forget to donate(we have no affiliation, just like useful applications like everyone else).