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In Windows 7 (x64) there are occasions when I'm running some sort of CPU intensive process like applying filters in Photoshop, etc that take several minutes to run. If I look in the resource monitor I don't see much CPU usage, perhaps 5-10% per core, a few gigs of free RAM, and little disk usage. Obviously the computer is doing work, my question is why isn't that reflected in the stats?

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migrated from serverfault.com Aug 21 '11 at 8:46

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Do you have a cuda supported GPU ? – Lucas Kauffman Aug 21 '11 at 7:19

If the task is not multi-threaded then it will "bounce" between cores but it will only be able to actually use 1 core at a time. You will likely see that the process itself uses about 25% CPU time on a 4-core processor (i.e. 1 processor fully in use) or about 12.5% CPU time on an 8-core processor.

Showing this kind of CPU usage per-core distorts this CPU usage somewhat as (as I mentioned) the process is does not necessarily always stick to the same core.

5-10% per core (call it 7.5% average) * 4 = 30% overall cpu usage

Which is what I'd expect to see for a quad-core system running one heavy single threaded task along with some background system tasks.

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