CPU usage when using two displays vs Clamshell mode

[Random Gecko]

I've recently got a 24" display that I'm connecting to my MBP via the mini display port, and running two screens. Generally I have the MacBook on the desk and the monitor elevated and run them both on at the same time. However, I'm noticing the fans are often spinning like crazy so I was curious whether, if I were to run the laptop in clamshell mode, would I see a reduction in what I presume is over-use of the CPU?

Basically, would it stress the machine less in Clamshell as opposed to running dual monitors?

 

[JTToft]

Basically, would it stress the machine less in Clamshell as opposed to running dual monitors?

- All else being equal, yes, running one display will tax the machine less than running two.

 

[venom600]

You can't overuse the CPU, the fans are supposed to come on whenever it gets too warm. It's doing what it's supposed to do, and dual monitors isn't going to change that much.

The question is, what are you doing when the computer gets warm? I've found that something like a time machine backup or an errant flash ad can do it. Try opening Activity Monitor (in your Utilities Folder in the applications folder), click the CPU tab, and sort by %CPU. That tells you what applications are using the most CPU at any given moment, so you might find that some innocuous app in the background is causing the higher than normal CPU use.