What don't you understand?    1 x Radeon Card 7990 has a fluctuating Mhash - is this normal?   I'd thought each gpu core of the 7990 would  mine at around 500 Mhash .     but there up and down like a tart's knickers.. also getting the 'connecting' alot on the GUIMiner.. maybe I should try a different software miner ??  ?