280x Toxic ethereum low hashrate.

[salvo.pyd]

Hi everyone 
I bought a 280x Toxic and i'm going to get it working properly.
I wanted to mine some ethers but unsuccesfully I'm not getting the hoped hashrate..
No overclock or underclock the gpu pulls just 20.3MHS pooled mining and 26.5MHS in benchmark mode.
I tried ubuntu 14.04 fglrx 15.20 (ccc 15.7) but the same thing, 20.3MHS. I took some photos to gpuz, I think the problem is the psu (cooler master 650W http://www.newegg.com/Product/Product.aspx?Item=N82E16817171014) because in full load it takes just 180W as shown by gpuz.
Any help will be very appreciated
https://15254b2dcaab7f5478ab-24461f391e20b7336331d5789078af53.ssl.cf1.rackcdn.com/ethereum.vanillaforums.com/editor/58/eru5b22af329.png
Benching
https://15254b2dcaab7f5478ab-24461f391e20b7336331d5789078af53.ssl.cf1.rackcdn.com/ethereum.vanillaforums.com/editor/nv/aztavbp7dfgj.png

[Zeelotin]

I think you need to reduce the memory frequency to 1500 MHz. For Ethereum mining, 1500MHz is fast than the 1600MHz.

[klondike_bar]

youre in the expected 18-22MH range.  my understanding is the benchmarks are based on a 1GB DAG file, rather than the ~1.3GB it actually is now

[fricircled]

Your Core frequency is quite high. There is no need for that to be too high, it is fine with 1050 MHz.

[Za1n]

I have several 280X's mining and I agree with what the others have posted, lower your core as it only adds more heat and power consumption, 1000 is even fine, also lower your memclock to 1500. I played with tons of settings and they only make the most minute differences in hash-rate, so you are better off saving on the power consumption.

As far as the hash-rate. yes with the increasing size of the difficulty/DAG file, 20.3 MHash is pretty average. I am getting ~ 21 MHash per 280X right now, down from 25-26 MHash about a month or two back.