unofficial CF overclocking method..
Here is a method that should allow you to overclock 2 x 2900XTs in CrossFire. Its not user-friendly (as there are quite a few steps involved) but should get the job done for now...
1st step is to download the GPUClocktool (
LINK)
Extract the zip file and then copy the attached DLL (from the attached ZIP file) to the same folder (replaces the original DLL).
Then follow these steps:
1) disable CrossFire from CCC
2) bring up display properties and select display #2 (this would be the display that is connected to the 2nd GFX card)
3) extend your desktop to this 2nd display and hit "APPLY"
4) select "use this device as primary monitor" (for 2nd display), go back to display #1 and UNCHECK "Extend my desktop onto this monitor" THEN hit APPLY
5) now your primary card should be displaying blank image and the 2nd card is active, CONNECT your monitor cable to the 2nd GFX card and you should see your desktop and Windows again
6) open GPUCLocktool, select "3D clocks" and select the proper card from the drop down menu (the proper card is the one that gives you a proper 3D clock reading (e.g. 743/828 for example)
7) set GFX clocks to desired values (example 850/950) (NOTE: it will give an error saying "SetClock Failed" - you can ignore this, the clock adjustment works)
8) now your 2nd card is clocked to the right speed, now redo steps 2-5 and restore your desktop to the 1st GFX card and then connect the monitor back to the 1st card
9) again open GPUClocktool, select "3d clocks" and select the proper card (which should still have default 3D clocks) and adjust the 3d clocks to desired values (850/950 for example)
10) start CCC and ENABLE CrossFire
A quick way to confirm that your really clocked both cards is to run 3DMark06 HDR1 test (Canyon flight) first with default clocks and then after the adjustments.
Here is how much I gained going from 743/828 to 850/950 (using a 3G CPU):
