Very good point regarding the temperature. In the 8-GPU machine, mine are usually around 60-70 Celsius
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 410.93       Driver Version: 410.93       CUDA Version: 10.0     |
|-------------------------------+----------------------+----------------------+
| 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 RTX 208...  Off  | 00000000:1A:00.0 Off |                  N/A |
| 41%   66C    P2   259W / 250W |   4429MiB / 10989MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce RTX 208...  Off  | 00000000:1B:00.0 Off |                  N/A |
| 43%   69C    P2   247W / 250W |   4429MiB / 10989MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+
|   2  GeForce RTX 208...  Off  | 00000000:3D:00.0 Off |                  N/A |
| 30%   49C    P2   134W / 250W |   4365MiB / 10989MiB |     84%      Default |
+-------------------------------+----------------------+----------------------+
|   3  GeForce RTX 208...  Off  | 00000000:3E:00.0 Off |                  N/A |
| 30%   47C    P2   127W / 250W |   4365MiB / 10989MiB |     79%      Default |
+-------------------------------+----------------------+----------------------+
|   4  GeForce RTX 208...  Off  | 00000000:88:00.0 Off |                  N/A |
| 36%   59C    P2   250W / 250W |   4429MiB / 10989MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+
|   5  GeForce RTX 208...  Off  | 00000000:89:00.0 Off |                  N/A |
| 35%   27C    P0    69W / 250W |      0MiB / 10989MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   6  GeForce RTX 208...  Off  | 00000000:B1:00.0 Off |                  N/A |
| 39%   62C    P2   252W / 250W |   4429MiB / 10989MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+
|   7  GeForce RTX 208...  Off  | 00000000:B2:00.0 Off |                  N/A |
| 38%   62C    P2   242W / 250W |   4429MiB / 10989MiB |     99%      Default |
+-------------------------------+----------------------+----------------------+

where the throttling is to occur at 89C:
        GPU Shutdown Temp           : 94 C
        GPU Slowdown Temp           : 91 C
        GPU Max Operating Temp      : 89 C

Could be that your cooling is not sufficient and you approach the Slowdown/Shutdown temperature  when you are running your GPUs, which could be an explanation for

My machine can only run for less than 10 minutes.

Maybe do a new run and keep an eye on the nvidia-smi reported temperatures and see if there is a correlation