Well it does seem like an extremely high proportion of stale and duplicate work. I know this isn't related to hardware errors but there is one miner which seems to be producing a relatively high percentage of HW errors also. I didn't screenshot that as it's only about 1.6%.
You're misreading the graph. Hashrate and rejects have different scales, one on the left side, the other one on the right side. Under 1% of rejects is not high.
Ah, thanks for that. I guess I'm reading the numbers in the pop up info box wrong too? I've never used ghash.io before. Just out of interest, what difficulty should be set for S3 use on ghash.io? My ghash.io account defaulted to 1024 initially but I thought this to be too high, so set it to 256 like it was with vardiff on Eligius.
256 is fine and 1024 is ok too I think. If you go higher than that the hashrate chart will be choppy and if you go lower you might get bottlenecked by network and/or controller.
You need to match the stale/dup numbers against the number of diff 1 shares submitted. You are submitting ~300,000 shares per round and occasionally getting ~2000 shares rejected in some rounds... perfectly fine as far as I can see.