There are several power profiles that can turn off some cores for saving energy consumption.
These are called NVP profiles. If you click on the NVIDIA icon in the desktop top bar on the right side, you may be able to select another NVP profile such as MAXN that has no limitation.
Also note if you’re looking for max perf and don’t care for energy savings that after switching to a NVP profile, you can boost the clocks with:
sudo jetson_clocks