Windows 7: System process eating up the CPU

My home computer is a 3yo machine running Windows 7 Ultimate x64. A couple days ago, the SYSTEM process started running at 100%.

After playing all the usual games (disabling services, updating drivers & antivirus, rolling back, safe-mode, etc etc), I finally said "screw this", reformatted and reinstalled.

But the problem persisted. Let me be clear: a week ago, the system was fine. Now, even after a clean install, with no updates or new drivers or anything, the problem is there.

So I tried Windows Server 2008 R2 x64, Windows 8 x64, Windows Vista Ultimate x64... even Knoppix linux. No other OS has any issues.

But under Windows 7, even on a completely clean and fresh install, the SYSTEM process is gobbling up 100% cpu time.

And it's just about to drive me insane.

At this point, I figure it has to be some driver interacting with hardware in an odd way. But which one?



Does anyone know how to drill down inside the SYSTEM process and see what's going on? (Without installing Visual Studio and bunch of debug files and all that.)

Thanks

Try Process Explorer ... Process Explorer

I tried Process Explorer, but unfortunately it doesn't let you drill down inside SYSTEM. It gives you the Interrupts thread and one other thing.. and that's it.

I figured it out. Ended up having to install the Windows SDK and use xperf and Windows Performance Analyser to track down the offending driver....

... Apparently Windows 7 no longer likes my USB 2.0 controller. Disabling the "enhanced" controller idled my CPU back down to 0%.

Which is no big deal since I don't often use USB drives. It is certainly odd, though.