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Pete, Computer Engineer
Category: Mac
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Experience:  Over 16 years of computer experience, CISCO certified
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CPU spikes every 5 seconds

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performance dataWhen I run graphics-intensive programs (games) on the windows side of my bootcamp partition, I get enormous lag spikes every 5 seconds. It does not matter what my graphics settings are. According to the resource monitor, these show up as spikes on CPU 1 from being parked to being at 100% and then back to parked again. I've not had this problem on the Mac side of the partition. And when I shut down the offending applications the spikes go away and CPU stays parked. What is happening, and is there anything I can do about it?


****** More info on my system:  imac11,1   27" imac with i7 cpu, 16GB RAM and on the windows side I have windows 7/64bit ********

I am Pete, and I'll be happy to assist with your question today.

When the CPU is spiking, check the Processes tab in the Resource Monitor and let me know which process is causing the spike.
Also let me know what graphics processor your iMac is using.
Chances are it is not powerful enough to run the graphics-intensive process or application.
Customer: replied 3 years ago.


Thank you for responding.

I tracked the processes for a long time. Here's what I did: I opened the task manager to the processes tab and sorted by CPU usage with the highest on top. I would leave it like this with the resource manager window open and watched which processes jumped to the top during a lag spike. Unfortunately there was no good correlation. The one that had the most movement was dwm.exe, which might make sense to you but none to me.

I have an ATI Radeon 4850. But as I mentioned in my post, it does not matter what the graphics settings are, from very easily rendered to very burdoned with low fps, the lag still occurs. I downloaded the latest driver from AMD directly again, just to make sure, and it still occurs.


The dwm.exe process is the Desktop Window Manager for Windows.

If it is spiking, too many windows may be open at once. This would put a burden on the CPU rather than the GPU, as you are experiencing.

The dwm.exe process is not essential - it is used by Windows to provide the transparent or 'glass effect' look to Windows.

You can turn it off by clicking on the Windows Start button, then type services.msc and press Enter to open up Windows Services. Find the "Desktop Window Manager Session Manager" service in the list, and click the stop button to temporarily stop it until Windows is restarted or you start it manually within Services again.

If you want to permanently disable it, double click it and select 'Disabled' as the Startup type.


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