+/- before the Memory Clock value indicates an offset memory clock. If it is simply the number, it indicates a locked memory clock.
Command Line Launch String:
Replace [Wallet] with your wallet address and [Worker] with your worker name
t-rex.exe -a octopus -o stratum+tcp://pool.us.woolypooly.com:3094 -u [Wallet] -w [Worker] -p x --lock_cclock 570 --mclock -500