CRABE and Flash
Now that we’ve found the maximum frequencies our Radeon can handle, it’s time to make the overclocking permanent by writing it to the BIOS. The procedure is very similar to what we did for the GeForce card. But it requires specific software, since the GeForce BIOS editors aren’t compatible with Radeon.
As before, the first stage is to save the card’s original BIOS settings. There are different programs capable of doing that. One of the best known is GPU-Z, which can also provide you with all kinds of information about the card. You extract the BIOS settings by clicking the little green arrow to the right of the BIOS version number.
The .bin file that’s created can be modified using CRABE (Computer base Radeon Bios Editor), the Radeon BIOS editor put out by our colleagues over at Computer Base. This utility is extremely simple to use, as you’ll see as soon as you launch it. All you do is set the cursors to the frequencies you want (and also, in this case, the voltage) and save. To avoid errors, the modified file automatically gets saved with the suffix _mod.
This file then needs to be written to the EEPROM on the graphics card. Once again, you copy it to a bootable removable medium (a diskette or USB key) and reboot to that medium. In addition, the medium also has to contain the original BIOS settings and the flashing utility. In this case it’s ATIFlash, a program created by ATI themselves. After reboot, enter:
ATIFlash -p -0 -newbios rv670_mod.bin -f
Press Enter and... voilà!