Activity monitor columns, what is difference?

A column for each core makes sense, but... At work I just got a new 3.2GHz Core i3 21.5-inch iMac. Presumably dual core? It's showing FOUR bars in the Activity Monitor's CPU Usage screen. In contrast, in June I got a 2.8GHz Core i7 27-inch iMac. Four cores, but the Activity Monitor's CPU Usage screen shows just one "bar"/graphic. Activity Monitor version 10.6 (212) on both Macs.

Any idea why the differences here?

At work I just got a new 3.2GHz Core i3 21.5-inch iMac. Presumably dual core? It's showing FOUR bars in the Activity Monitor's CPU Usage screen.

Some of the newer Macs have hyper-threading, which makes each core appear to be two processors.

Your CPU has two "cores" which can work more or less independently. The two columns show how much each core is getting used.

charlie

A column for each core makes sense, but... At work I just got a new 3.2GHz Core i3 21.5-inch iMac. Presumably dual core? It's showing FOUR bars in the Activity Monitor's CPU Usage screen. In contrast, in June I got a 2.8GHz Core i7 27-inch iMac. Four cores, but the Activity Monitor's CPU Usage screen shows just one "bar"/graphic. Activity Monitor version 10.6 (212) on both Macs.

An intel 2-Core "Core 2 Duo" can support 2 threads of execution.

The i3, i5, i7 processors all support hyper-threading, which means each core can support 2 concurrent threads of execution. So your 2-Core i3 can run 4 concurrent threads.

The 4-Core i7 can support 8 concurrent threads of execution.

In addition, my 27" iMac i7 Activity Monitor floating window shows 8 bars of CPU activity, so I do not know why your's is only showing 1 bar.

In addition, my 27" iMac i7 Activity Monitor floating window shows 8 bars of CPU activity, so I do not know why your's is only showing 1 bar.

If I pull-up the floating window it does show 8 bars (had not looked at this before...). It's the usage graphic at the bottom of the Activity Monitor window, and the Dock icon, that shows a single block on my 4-Core i7, but 4 bars on my new 2-Core i3 at work. Unless your i7 is showing more there, I'm guessing Apple decided this graphic would be meaningless cramming 8 bars into it & left that to the floating window. I had not been aware of the hyper-threading, so that makes this much clearer. Thanks!