2010 iMac Fans Dont Speed Up

That's normal and done by design. If the fans need to go faster to remove heat, they will. There's no need to manually increase the fans speed as the heat won't damage anything.

 

Your fans may or may not spin faster. They do so only as necessary to keep temps in a safe operating range. 150F/65C is not particularly hot, so it's not surprising that the fans aren't spinning faster at that speed.

If you're not already doing so, use iStat Pro (free) or iStat Menus ($16) to get accurate readings of your temps, fan speeds, etc., rather than relying on your sense of touch or sound. A forum member has posted a copy of iStat Pro that has been "tweaked" to enhance compatibility with Mountain Lion. You can download it here.

The Intel processors used in Macs are designed to automatically shut down to prevent damage if they truly overheat. CPU Tjmax = 105C (221F), GPU Tjmax = 100C (212F) on i3, i5, i7 processors. (Source: Intel)

Unless there is a rare defect in a Mac, most temps are well within the normal operating range, considering the workload being put on it. Websites with Flash content, games and other multimedia apps will put higher demand on the CPU/GPU, generating more heat. This is normal. If you're constantly putting high demands on your system, such as gaming or other multimedia tasks, expect temps to rise and fans to spin up accordingly. It's just your Mac doing its job to maintain temps within the normal range.

It is also quite normal for your Mac to become extremely hot to the touch during intensive operations. The aluminum body transfers heat more effectively than other materials used in computer casings, so you will feel the heat more. This doesn't indicate that it's overheating and will not harm the computer to be hot to the touch.

Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). iMacs have 3 fans with minimum speeds in the 800-1200 range. They will spin faster as needed to keep temps at a safe level.

If your fans are spinning up without increased heat, try resetting the SMC.
(PRAM/NVRAM has nothing to do with these issues, so resetting it will not help.)

The intake and exhaust vents are in the back of the computer near the hinge on all Mac notebooks (except the new MBP with retina display, which has intake vents along the sides at the bottom). The iMac vent is a slot on the back near the top of the computer. Make sure the vents remain unblocked to allow your computer to perform at its best.

Learn about the fans in your Mac
Apple Portables: Operating temperature

For Flash-related issues:

• Find your Flash version and make sure it's the latest version available.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Use the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.)

 

You can't manually set a fan speed. With apps like smcFanControl, you can adjust the minimum speed, but not set a specific speed. You really don't need to do that, as your Mac will automatically manage temps and fan speeds. It's quite normal for temps to get hot under heavy workloads. When your Mac starts shutting down due to temps, then you need to look at it. Otherwise, just relax and enjoy your Mac.

 

Those smudges were not caused by heat. They were caused by dust, being blown in from fans. The new iMacs have a vastly improved screen that is better sealed against such dust. Increasing the fan speed will likely increase the chance of getting those smudges.

 

shutting down

ok... I've had my iMac since 2007, it's the 20" intel duo, I've upgraded the RAM to 3gb and upgraded the HDD to 1tb, everything has been working great until about the last 2 months. Now when using the iMac it will shutdown at random during use. I never hear the fans speed up but suspect it's due to heat...??? I've done the SMC reset several times and it still kept shutting down. I installed SMC fan control and bumped the fan speeds up and it has not shut down again...??? I tried the Derman iMac Fan Control but the CPU and GPU temperatures never worked and only read 32 degrees farenheit. I like the Derman idea in that it speeds the fans up when needed and lets them slow down when not... I've been told SMC only sets a specific speed and that's it. Is there a program like Derman's that is updated? I have 10.7.5 and Derman's website says it's only designed to work with 10.4.
Can anyone tell me how to get the CPU and GPU temps to read with Derman, or is there another program out there that will work???