Activity Monitor saying my CPU usage is 153.5% ???

How can one program use more CPU than I have? What is that percentage based on? I see at the bottom it also says "% Idle: 78.39". I'm confused.

I went in there to see how much RAM Final Cut Pro is using since it is dropping frames during playback and saw that CPU usage.

Regarding RAM usage, what does "Swap used" mean? Is it using one of my hard drives as memory since I'm running out? (I am in the process of ordering 8 more gigs, only have 4 now)

TIA for any help.

I believe the CPU usage is calculated by the number of cores in your machine. So, if you have a quad-core machine, that is 4 CPUs. So 100% for each CPU gives you 100% x 4 =400% possible CPU usage.

Chef_eam said:

I believe the CPU usage is calculated by the number of cores in your machine. So, if you have a quad-core machine, that is 4 CPUs. So 100% for each CPU gives you 100% x 4 =400% possible CPU usage.

Click to expand...

This is correct. Each core of your processor counts as one processor. So, if you have a dual core machine, you can have 200% CPU usage. It's a bit odd but it makes sense when you understand how CPU usage is calculated.

Chef_eam said:

I believe the CPU usage is calculated by the number of cores in your machine. So, if you have a quad-core machine, that is 4 CPUs. So 100% for each CPU gives you 100% x 4 =400% possible CPU usage.

Click to expand...

Weird. But that makes the numbers seem right. With 8 cores 150% would be 18.75% of all 8 cores together. And that's just for FCP, so then the 78.xx% free makes sense.

Thanks.