Windows Driver Issue on Quad (i5 & i7) iMacs
As you may know, I’ve been having fun with Windows lately — first Vista and then after despair, XP. I thought I had everything going pretty good — except that every time I looked at the Task Manager, I had one CPU core running at 100%. Hmm, that’s odd…
I did a lot of digging around on this one. I was able to figure it out, with the help of a few tools: the excellent Process Explorer, which is a part of the Sysinternals package and the RATTv3 tool which is also available from Microsoft. Using these tools, I was able to find out that the acpi.sys driver was what was taking up all the CPU usage. I had found some suspect advice on the net saying that you could simply suspend the kernel thread for acpi.sys using Process Explorer, and that did indeed work. But that’s only a temporary band-aid fix. I really wanted to know what the problem was being caused by.
Armed with my new found knowledge, I did a search for “imac 27 quad acpi.sys” in Google. Bingo.
Turns out the issue is being caused when you have a cable plugged into the headphone jack, which in my case, I do. Something with the Apple provided driver appears to not like having the jack occupied, and causes it to shoot one of the CPUs up to 100%. Unplugging the cable fixed the issue for me now. Now I just need to wait for updated drivers to fix the problem for good.
