Windows 7: #3 CPU Spikes

Hey, i just noticed (no idea how long this has been going on for) every few seconds CPU #3 (none of the others, 1, 2, 4) spikes to 100% for about 2 seconds then drops back down in almost a timed fashion, as you can see from this screen shot below....Any ideas on what this can be? (i also confirmed from resource monitor, so its not just the gadget)





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If you look at it with resmon, is it any one process specifically that spikes up during this time?

It is not unusual that the cores are unevenly used. During certain operations, it is often one or the other core (or a combination of 2) that takes the load. As Cluberti says, find the process. You can also look into Resource Monitor > CPU tab - just let it run in a reduced size window.

Everytime the core #3 spikes "System Interrupts" spikes to 25% of my total cpu (using all of the third core, with 4 cores)

how can i tell what is causing this?

Run this program ( DPC Latency Checker ). If you get red bars, you most likely have a driver problem.

You can also run Process Explorer for a quick check. If the DPC (deferred procedure calls) runs a lot (more than 1%), then you may have the stated problem. The DPC process is normally the third from the top.

BTW....using 100% of a core is in fact a good thing. Why spend all that money if you are never going to fully utilize that hardware? As you said it last for about 2 seconds, from that it doesn't sound like something you should be concerned about. Especially when you are running all those applications.