TechPowerUp reports AMD pulled another stunt, as it appears that Radeon HD 6790 retail cards have more ROPs then they should have. The card is supposed to have 16 of the 32 ROPs on the 40nm Barts GPU enabled, but it appears that the company "accidentally" shipped units with 24 out of 32 ROPs enabled.
The issue surfaced when GPU-Z started reading ROP count of our samples as 24, even as AMD press deck and subsequently the product page on AMD website mentioned HD 6790 ROP count as 16. We initially dismissed it as a GPU-Z bug, but as it turns out, HD 6790 indeed has 24 ROPs enabled, if GPU-Z reads so. An ROP (raster operations processor) handles a key part of the GPU's geometry rendering. ROPs process final shader output pixels and put them into memory. 24 ROPs theoretically gives these few HD 6790 cards 50% higher geometry processing power.