# NVIDIA Tesla GPU - Power Brake

```bash
nvidia-smi -q | grep HW
        HW Slowdown                       : Active
            HW Thermal Slowdown           : Not Active
            HW Power Brake Slowdown       : Active
```

Your server vendor may block GPUs not on a HCL. HW Power Brake Slowdown on NVIDIA Tesla GPUs is documented with a fixed slowdown of 50% in performance and power limit (see Data Sheet).

You can prevent the system from activating the "HW Power Brake" by blocking PCIe Pin B30. Pin B30 has been a reserved pin for long time. This has changed to Pin B30 being a PWRBRK for emergency power reduction.

[![image.png](https://wiki.isunreal.de/uploads/images/gallery/2024-04/scaled-1680-/6HxFsZRlBHdpq8CD-image.png)](https://wiki.isunreal.de/uploads/images/gallery/2024-04/6HxFsZRlBHdpq8CD-image.png)

Source: [https://pcisig.com/specifications/pciexpress/](https://pcisig.com/specifications/pciexpress/)

Tape or use a waterproof marker to block Pin B30. B30 is on the cooler side 30th Pin.

```bash
nvidia-smi -q | grep HW
       HW Slowdown                       : Not Active
            HW Thermal Slowdown           : Not Active
            HW Power Brake Slowdown       : Not Active
```

[![image.png](https://wiki.isunreal.de/uploads/images/gallery/2024-04/scaled-1680-/GGYgmooGX8xgzMZW-image.png)](https://wiki.isunreal.de/uploads/images/gallery/2024-04/GGYgmooGX8xgzMZW-image.png)