To miners who have HD7970 or 280X. You Can easy set 715Mhz core clock, hashrate it's like with 835MHz core or more, but you can undervolt your card to only 900mV..
Only memory clock to 1500Mhz.
Which software do you use to change the card settings?, I have 2 sapphire dual-x 280x and with MSI Afterburner I cant change the voltage, only the core and memory mhz.