This is a known observation in Windows 10. I'm not sure why the Task Manager always reports a higher value, but:
- HWiNFO uses standard methods to determine the per-thread and total CPU utilization. The same method that works since Windows XP or so and has always been reliable.
- I have done several tests using fixed workloads and compared the values. HWiNFO always matched the expected workload (i.e. putting 100% load on 50% threads, it reported ~50% total load), but the Windows Task Manager has always been over-reporting.
So in my opinion HWiNFO shows the correct value.