Got a 2nd miner running but finding very little shares

[Girac]

My ist miner has 4 GPU and I find between 80-100 shares per hour with that running 115 M/hs. the 2nd one is running on claymore on windows and running at 28M/hs but finding 1 share like every 10-15 minutes. Eventually this will be running on Ethos when my new 8 gpu mb comes. until them i thought I run on windows.

Is there anything I can do to increase my share finding?