did you put memory to the lowest clock possible?
about low difficulty, try adding this:
EDIT: you should use -k diamond and rename groestlcoin.cl to diamond.cl
no, memory runs at 1450(1st card) and 1250(2nd card).
adding difficulty-multiplier results in much faster output of rejected shares.
renaming groestlcoin.cl to diamond.cl and running sgminer-5.4.0 with -k diamond gives same low hashrate(11 and 12) unless i rebuild bin file. That works !!!! Thank you so much Pallas. Going to put a positive feedback for your endless help.
What sgminer version do you use ?