Extending ATI OC limits on the example of HD 4770

I prefer AMD products in video card choice. There are plenty overclocking software made for these cards, these cards are good at overclocking while providing awesome performance. But there some negative points. Let′s say, they overclock well, but the level of overclocking is limited to maximum frequency than is set by overclocking limits in ATI Overdrive.

AMD limits the overclocking of their products for reasons unknown. Limits are flashed inside card′s BIOS as an encrypted key. Driver checks key and set limit compatibility. If limits don′t match the key — the card′s driver won′t function. The keys are distributed by AMD only, therefore, even vendors releasing video cards based on AMD GPUs can′t change limit values without AMD′s approval.

If it obvious that there is more room for card overclocking that limits allow then BIOS needs to be modernized. First of all, download this excellent AMD videocard BIOS editing tool — RBE. This editor allows setting of absolute limit values:

That doesn′t suit us for the reasons stated before — driver doesn′t recognized the cards that has modified limits, i.e. driver checks new limits and encrypted key which leads to driver failure.

However, this editor can save and overwrite whole BIOS area which includes information about limits together with encrypted key. For that, select hash editing method:

After a quick examination of the BIOS editor, new BIOS of same GPU but with extended limits is required. Generally, it will be Asus cards with the TOP index that have such BIOS.

So, search for the appropriate BIOS inside the techpowerup database, then open it using RBE. Next, go to the last tab and choose limit hash editing through hash overwriting and save Asus TOP BIOS hash:

There is no need for other card BIOSes now. Now open you native videocard driver in the editor. Once again go to the last tab, choose hash overwriting method, only this time, load Asus TOP hash that was saved earlier:

All left is to save edited BIOS and flash the card. Before that, make sure to check modified BIOS in RBE!!!