2x r9 280x Hash is low?

Hi,

Am new to ETH mining, been mining about a week with MinerGate - on 1 of my cards.

I have ordered 4x r9 280x soon doing my first mining rig.

I am experiencing very low hases,

At the moment am running 2x r9 280x , one is Matrix Platinum and one is Direct CU II TOP each average around 24-25mh's but together i only get 30?

Where am i going wrong...

Thank you!