Radeon HD 4870 X2 overclocking put to the test
The stock frequencies are the same as with Radeon HD 4870, although Diamond earlier announced the XOC version which not only operated at higher frequencies it could also be overclocked further than any other Radeon HD 4870 on the market.
guess2098 made some BIOS modifications and was able to up the frequency to 850MHz core clock and 4000MHz memory clock. One thing that you should make sure to remember though is that this card (Rev2) uses Hynix GDDR5 chips, not Qimonda (Rev1). Partners can choose either memory type, and we will have to wait for reviews to determine which of the two is preferred.