nVidia cards=Raise all values
ATi cards=Drop mem
Now then, The best bang for buck cards are ACTUALLY not the 58xx's
It is the 5830's!!
Im running a $114 Shappire 5830 @260mhashes. Beat that!
the $140XFX ones hit 290mhashes wich is Much better.
I have a Dual 6990 rig and i regret it, Each core pulls 334mhashes and each card has two gpus, So 1300mhash/sec, Cards were 750ea
AND THE MOTHER FUCKERS ARE HOT, 100°'s when fan speeds are at 100%, and the case has around 8fans in it aswell. Altough, if i take off the sidepanel, And stick a Massive desktop fan right next to it (the really big ones 120V 50W) then the fan speeds drop to 80% and the temps drop to a beautiful 85°.
Do not buy 6990's unless you are accounting for Moores Law,
If your just mining, Buy a fuckload of 5830's, They run cold, Overclock well, And suck at gaming, PERFECT MINING CARD
https://en.bitcoin.it/wiki/Mining_hardware_comparisonMy 6990 does 420mhash/core so you might want to check your settings. But i agree 5830s are more bang for the buck