As you would expect, the Sapphire Vapor-X HD 4890 comes factory-overclocked, but only midly. Its core clock speeds have received a 20MHz bump from 850MHz to 870MHz, whereas memory clock speeds have been improved more significantly to 4200MHz DDR as compared to a stock card's 3900MHz DDR. It should be noted that these clock speeds are bit on the conservative side, considering the overclocked Sapphire HD 4890 that we've reviewed earlier this year came clocked by default at 900MHz at the core and 3900MHz DDR at the memory. Given the superior cooling technology on this card, we expected more. Still, this should give us some boost in performance.
Aside from the increased clock speeds, the Sapphire Vapor-X HD 4890 is also one of the few Radeon HD 4890 cards to come with 2GB of framebuffer. To be honest, we are not sure if today's applications will be able to make full use of the full 2GB of video memory, and we doubt it will offer any substantial increase in performance over cards with a 'mere' 1GB of framebuffer. Guess we'll find out soon enough.