We've received many e-mails over the last few months regarding how to overclock two Radeon HD 2900 XT in CrossFire mode. Unfortunately we haven't had a good answer for you, but with some help from macci, now a resident of AMD/ATI, we can now present this guide, which shows you how to overclock Radeon HD 2900 XT when you have two of them running in CrossFire mode. No need for any flash tools or BIOSes. All you need is the AMD GPU Clock Tool and an updated toollib.dll file.
The approach is far from simple, but not hard to perform. It just takes time, and considering how much you have to gain we definitely think it's worth the effort. However if you're using more exotic cooling, such as dry ice or liquid nitrogen, this is not a very good approach, since it takes so long to perform. We've also compiled some tips and troubleshooting information for you if things don't go as planned.
This article is a based on information posted by macci, and the pictures were used with his consent, but have been completed with some general overclocking tips and information about CrossFire overclocking.
