CUDA only recognizes 1 of 5 GPUs - tensorflow

Question

I would like to run tensorflow on a windows 10 server with 5 NVIDIA Quadro P6000 GPUs. After installing CUDA 8.0 and running deviceQuery.exe it only shows one of the GPUs and therefore tensorflow only uses one GPU as well.
(tensorflow-gpu) C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v8.0\extras\demo_suite>deviceQuery.exe
deviceQuery.exe Starting...
CUDA Device Query (Runtime API) version (CUDART static linking)
Detected 1 CUDA Capable device(s)
Device 0: "Quadro P6000"
CUDA Driver Version / Runtime Version 8.0 / 8.0
CUDA Capability Major/Minor version number: 6.1
Total amount of global memory: 24576 MBytes (25769803776 bytes)
(30) Multiprocessors, (128) CUDA Cores/MP: 3840 CUDA Cores
GPU Max Clock rate: 1645 MHz (1.64 GHz)
Memory Clock rate: 4513 Mhz
Memory Bus Width: 384-bit
L2 Cache Size: 3145728 bytes
Maximum Texture Dimension Size (x,y,z) 1D=(131072), 2D=(131072, 65536), 3D=(16384, 16384, 16384)
Maximum Layered 1D Texture Size, (num) layers 1D=(32768), 2048 layers
Maximum Layered 2D Texture Size, (num) layers 2D=(32768, 32768), 2048 layers
Total amount of constant memory: 65536 bytes
Total amount of shared memory per block: 49152 bytes
Total number of registers available per block: 65536
Warp size: 32
Maximum number of threads per multiprocessor: 2048
Maximum number of threads per block: 1024
Max dimension size of a thread block (x,y,z): (1024, 1024, 64)
Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535)
Maximum memory pitch: 2147483647 bytes
Texture alignment: 512 bytes
Concurrent copy and kernel execution: Yes with 2 copy engine(s)
Run time limit on kernels: Yes
Integrated GPU sharing Host Memory: No
Support host page-locked memory mapping: Yes
Alignment requirement for Surfaces: Yes
Device has ECC support: Disabled
CUDA Device Driver Mode (TCC or WDDM): WDDM (Windows Display Driver Model)
Device supports Unified Addressing (UVA): Yes
Device PCI Domain ID / Bus ID / location ID: 0 / 4 / 0
Compute Mode:
< Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) >
deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 8.0, CUDA Runtime Version = 8.0, NumDevs = 1, Device0 = Quadro P6000
Result = PASS
However, nvidia-smi.exe and GPU-Z do recognize all 5 of them.
(tensorflow-gpu) C:\Program Files\NVIDIA Corporation\NVSMI>nvidia-smi.exe
Wed Sep 27 11:07:44 2017
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 376.51 Driver Version: 376.51 |
|-------------------------------+----------------------+----------------------+
| GPU Name TCC/WDDM | Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 Quadro P6000 WDDM | 0000:04:00.0 Off | Off |
| 26% 45C P5 19W / 250W | 353MiB / 24576MiB | 3% Default |
+-------------------------------+----------------------+----------------------+
| 1 Quadro P6000 WDDM | 0000:05:00.0 Off | Off |
| 26% 24C P8 7W / 250W | 69MiB / 24576MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
| 2 Quadro P6000 WDDM | 0000:08:00.0 Off | Off |
| 26% 26C P8 8W / 250W | 69MiB / 24576MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
| 3 Quadro P6000 WDDM | 0000:09:00.0 Off | Off |
| 26% 26C P8 8W / 250W | 69MiB / 24576MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
| 4 Quadro P6000 WDDM | 0000:89:00.0 Off | Off |
| 26% 22C P8 8W / 250W | 262MiB / 24576MiB | 0% Default |
+-------------------------------+----------------------+----------------------+
+-----------------------------------------------------------------------------+
| Processes: GPU Memory |
| GPU PID Type Process name Usage |
|=============================================================================|
| 0 2640 C+G Insufficient Permissions N/A |
| 0 3908 C+G ...x86)\Google\Chrome\Application\chrome.exe N/A |
| 4 2640 C+G Insufficient Permissions N/A |
| 4 3552 C+G ...\ImmersiveControlPanel\SystemSettings.exe N/A |
| 4 5260 C+G Insufficient Permissions N/A |
| 4 6552 C+G Insufficient Permissions N/A |
| 4 7208 C+G ...ost_cw5n1h2txyewy\ShellExperienceHost.exe N/A |
| 4 7444 C+G ...indows.Cortana_cw5n1h2txyewy\SearchUI.exe N/A |
+-----------------------------------------------------------------------------+
Does anyone have an idea what I could try to make all of them work for CUDA and tensorflow?