If i where you try cgminer and see how much that does
For more options start cgminer as follows : cgminer --help
Its so full of options too much to mention here
I personally used on my 5870 : () means you need to replace it fully example -u tester -p x
cgminer.exe -v 2 -w 128 -I 7 --gpu-engine 900 --gpu-memclock 450 -o http://mint.bitminter.com:8332
-u (pool username) -p (password used)
If you run windows save it into a miner batch or cmd file so you can start it in a easy way
My sapphire 5870 toxic makes about 440 Mh/s running at 920 Mhz core and 450 Mhz memory with cgminer ofcourse the average speeds are not consistent cause there are too many factors involved
Now i have run this 5870 at 940 Mhz without problems but i see the usage of electra go up so high i think its not worh doing.
I think more important is have a efficient miner which uses not so much electra but with a good average.
Now lol i have a 4770 still running and i had made a copy error it ran 15 minutes at 940 Mhz on the cmd from my 5870
Seeing such a small card doing 108 Mh/s scared the hell out of me
I know some people get these cards well near or over 1000 Mhz but i really think its not good to do so, even stronger i think my cards can run these speeds also but again its useless because the power usage goes through the roof.