In the latest claymore ethereum miner I don't see an option for -a 2 or any -a at all, although i see a low intensity more -li (could use -li 2) is that what you mean by -a?
I'm not using the eth miner so i don't know about -li, but it might be similar, you should test.
-a is an option for Claymore's XMR miner :
-a Select algorithm:
"-a 0" (default) means autoselection.
"-a 1" fastest mining mode for 290/290x and 270/270x cards.
"-a 2" low power consumption mode for 290/290x cards. A bit less speed (1%) but less power consumption (10-15%).
"-a 3" fastest mining for old cards (6xxx and 5xxx).
"-a 4" fastest mining for recent cards (280x, 270/270x etc).
You can also specify mode for every card separately, for example, "-a 1234".
It is very important for good mining speed to select correct "-a" and "-h" values for your cards.
For old cards 5xxx and 6xxx use "-a 3" mode only, otherwise you can get "LowDifficultyShare" errors from pool.
