Quite long time ago I started to gather experience in this area:
https://archive.litecointalk.org/index.php?topic=18437.msg156242#msg156242And finally I have implemented real outdoor rig.
And one month of successfull testing now: rain, high humidity and temperature up to 30 Celsius degree.
It's the standalone solution - i.e. without any external roof. And it looks really stealthily.
(to keep it at night - I'm covering yet GPU's and mobo's LEDs with black adhesive tape)
It's 4x GPU rig (I'm using 4x GTX 1070). Configuration protects mobo and PSU against humidity.
Cost of material including cables, risers (excluding GPUs, mobo and PSU) - is ~35$
approx. dimensions: 45x57x57 [cm],
current example (rain, high humidity and 16 degree Celsius air):
root@kopiemtu:/opt/kopiemtu# nvidia-smi
Wed Aug 10 09:40:19 2016
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 3/67.27 Driver Version: 367.27 |
|-------------------------------+----------------------+----------------------+
| 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 Off | 0000:01:00.0 Off | N/A |
| 37% 67C P2 136W / 140W | 1121MiB / 8113MiB | 96% Default |
+-------------------------------+----------------------+----------------------+
| 1 GeForce GTX 1070 Off | 0000:02:00.0 Off | N/A |
| 32% 64C P2 137W / 140W | 1121MiB / 8113MiB | 99% Default |
+-------------------------------+----------------------+----------------------+
| 2 GeForce GTX 1070 Off | 0000:03:00.0 Off | N/A |
| 34% 65C P2 142W / 140W | 1121MiB / 8113MiB | 98% Default |
+-------------------------------+----------------------+----------------------+
| 3 GeForce GTX 1070 Off | 0000:04:00.0 Off | N/A |
| 37% 67C P2 135W / 140W | 1121MiB / 8113MiB | 98% Default |
+-------------------------------+----------------------+----------------------+