from readme of silentarmy miner:
Troubleshooting performance issues:
By default SILENTARMY mines with only one device/GPU; make sure to specify all the GPUs in the --use option, for example silentarmy --use 0,1,2 if the host has three devices with IDs 0, 1, and 2.
If some GPUs have less than ~2.4 GB of GPU memory, run silentarmy --instances 1 --use ... (2 instances use ~2.4 GB of GPU memory, 1 instance uses ~1.2 GB of GPU memory.)
If 1 instance still requires too much memory, edit param.h and set NR_ROWS_LOG to 19 (this reduces the per-instance memory usage to ~670 MB) and run with --instances 1.
go to ubuntu compile and install miner with that modification and it may work.