DEPENDING HOW HOT YOUR ROOM IS--

280X cards run hot and eat power.  If your cards are overheating, you may need to downclock, and earn 15-16MH/s per card.   If you set "-dcri 15" in your config, you will reduce the intensty of your secondary coin by 1/2  and give your 280X cards more room to breathe; they will run faster  and at lower temperature.  If you set "-cclock 1100", you will overclock your card, increase the hash rate, and increase the temperature of the card.  A core clock of 1100 may not be stable for your card/rig, you have to check postings by other miners regarding overclocking.  If you set "-tt 87", your card will self regulate, attempting to keep the temperature at or below 87 deg F.  If you are in a hot room, your hash may be 15-16MH/s because of temperature throttling.  My 280X cards made 22MH/s last winter, when the room was cooler, and the difficulty lower, and the DAG smaller.

All of this and more is in the README!!!.txt file, you should study it.       --scryptr