Need advice from Mister Claymore or someone else.
I'm mining now at ethermine.org (Europe (France): eu1.ethermine.org:4444)
The pool uses diff 40M

My 3-4 cards rigs are doing fine, but I have 2 standalone comps with only one 30mhs card in each. And this one-card rigs have huge (5-15%) stale share rate reported by pool. all rigs have identical and fast Internet access with the multi-card rigs, 70-100ms latency to pool. Is it due to high pool diff and low (30mhs) rig speed? Is there a way to fix this without changing a pool? I can't move this cards to multi-card rigs ((
 
I'm using latest Claymore 9.5 but older versions seem to behave the same.
Thanx in advance