fix makefile for multigpu setups

Makefile

@@ -49,7 +49,9 @@ endif
 ifneq ($(CI),true) # if not in CI, then use the GPU query
   ifndef GPU_COMPUTE_CAPABILITY # set to defaults if: make GPU_COMPUTE_CAPABILITY=
     ifneq ($(call file_exists_in_path, nvidia-smi),)
-      GPU_COMPUTE_CAPABILITY = $(shell nvidia-smi --query-gpu=compute_cap --format=csv,noheader | sed 's/\.//g')
+      # Get the compute capabilities of all GPUs
+      # Remove decimal points, sort numerically in ascending order, and select the first (lowest) value
+      GPU_COMPUTE_CAPABILITY=$(nvidia-smi --query-gpu=compute_cap --format=csv,noheader | sed 's/\.//g' | sort -n | head -n 1)
       GPU_COMPUTE_CAPABILITY := $(strip $(GPU_COMPUTE_CAPABILITY))
     endif
   endif