[375.26 Ubuntu 16.04 x64] Can't set parameters for 3rd GPU

I can set attributes for GPU0 and GPU1. But not GPU2. Throw Uknown Error. Any idea?

vondra@msiz250:~$ sudo nvidia-settings -a ‘[fan:1]/GPUTargetFanSpeed=81’

Attribute ‘GPUTargetFanSpeed’ (msiz250:0[fan:1]) assigned value 81.

vondra@msiz250:~$ sudo nvidia-settings -a ‘[fan:2]/GPUTargetFanSpeed=81’

ERROR: Error assigning value 81 to attribute ‘GPUTargetFanSpeed’ (msiz250:0[fan:2]) as specified in assignment ‘[fan:2]/GPUTargetFanSpeed=81’
(Unknown Error).

vondra@msiz250:~$ nvidia-smi
Thu Jan 26 13:10:21 2017
±----------------------------------------------------------------------------+
| NVIDIA-SMI 375.26 Driver Version: 375.26 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 GeForce GTX 1070 On | 0000:01:00.0 Off | N/A |
| 80% 58C P2 163W / 170W | 738MiB / 8111MiB | 99% Default |
±------------------------------±---------------------±---------------------+
| 1 GeForce GTX 1070 On | 0000:02:00.0 Off | N/A |
| 81% 55C P2 166W / 170W | 794MiB / 8113MiB | 99% Default |
±------------------------------±---------------------±---------------------+
| 2 GeForce GTX 1070 On | 0000:04:00.0 Off | N/A |
| 32% 58C P2 156W / 170W | 738MiB / 8113MiB | 98% Default |
±------------------------------±---------------------±---------------------+