A deadlock typically does not cause high CPU usage, at least not if the deadlock occurs in synchronization primitives that are backed by the OS such that processes sleep while they wait.

What causes high CPU usage?

You can expect high CPU utilization when playing some games, running a video-editing or streaming application, performing an antivirus scan, or juggling many browser tabs.

What is causing high CPU on SQL Server?

If you see % Privileged Time under the processor node is greater than 25 -30 %, it basically indicates that the processor is spending more time on executing kernel mode operations. There's possibility that a faulty system drivers or any antivirus software that is running currently is causing this.