Are my fans too loud?
There are times when my Late 2011 15-inch MacBook Pro’s fans seem to run at full speed with only iPhoto, Photoshop and a web browser open. The Mac has a very slim case on it, which does not interfere with the vents at the back. Is this a known issue? Martin Williams Photoshop can be demanding on the graphics processor if you are applying complex filters to a batch of images. Laptops always struggle more with cooling than desktops, because there’s much less room for airflow inside. Your MacBook Pro has two fans on its motherboard, and it’s possible that one of them has failed, which would make the remaining one work overtime. Even if both are working, dust gradually accumulates on the fan blades and on the motherboard itself, reducing cooling efficiency.
Search ifixit.com for how to open up your Mac. If a fan is faulty, you can often find replacements on eBay. Most likely, all you need to do is give the inside a good blow to get rid of the worst of the dust and then put the case back on. Don’t use a vacuum cleaner as these can generate static electricity than can harm the electronics. Compressed air cans are safer.
TechTool Pro (micromat.com) can test whether your Mac’s fans are still operational.