Windows XP SP3 on an AMD x2 processor. One of the cores appears to be run at 90-100% according to the Performance graph. The statusbar at the bottom says CPU Usage 50%. But when I look a processes It shows the System Idle Process at 96-99%. Network traffic is negligible. Any suggestions on how to find out what is each one of my CPUs would be appreciated1 person got this answerI do too

Check with Sysinternals Process Explorer. I'm wondering if you will notice Interrupts or DPCs having a high amount of CPU usage (which Task Manager will attribute to the System Idle Process).

Rebooting seems to have resolved the issue. If it happens again I'll try process explorer.