Originally Posted by LOL_Wut_Axel
And before anyone chimes in talking about over-clocks: we're comparing stock performance. Stock performance is what is used to determine if one card is faster than the other, and the HD 6990 has clearly won that.
Stock performance is very important. HOWEVER, there are cases when it would be silly to not take into account overclocked performance. For example, consider the 5970.
It shipped with clock speeds considerably lower than 5870 CF. But, pretty much every single card successfully overclocked to those speeds or higher. It was so common that it was an advertised feature for some of the cards.
If virtually every single GTX590 can successfully overclock to speeds just below, at, or above a GTX580, it would be naive to dismiss that from being a factor when comparing performance.