Why Mod The Card?

As I mentioned before, the 256MB Sapphire Radeon 9800 Pro is actually a Radeon 9800XT in disguise.

The hidden Radeon 9800XT features can be unlocked by just replacin the Radeon 9800 Pro BIOS with a Radeon 9800XT BIOS. This immediately turns it into a true 9800XT.

The most obvious changes are the increased clock speeds. By default, this card runs at 380MHz core and 340MHz memory. Once it is modded into a Radeon 9800XT, the card automatically clocks itself at 412MHz core and 365MHz memory. That's an instant increase of 8.4% in core speed and 7.4% in memory speed.

Depending on the situation, increasing the core clock speed can noticeably improve performance, especially when the pixel shader is heavily utilized. The increased memory clock speed will improve Anti Aliasing and Anisotropic Filtering performance due to high usage of memory bandwidth.

If you are of the 'adventurous' type, you can try overclocking the card further. Of course, you will need to improve the card's ability to cool the GPU!

The memory should be particularly overclockable since the card is using 2.5ns Hynix DDR memory chips, which are rated to run at 400MHz.

While some people claimed this mod actually improved the card's overclockability, I personally did not notice any improvement. In fact, I could not even get the card to run at stock Radeon 9800XT clock speeds! Of course, this was because I only used the stock cooler.

In any case, overclocking mileage varies from card to card. It is virtually impossible to compare or make judgements based on just one card.

But after switching from the original cooler to the cooler used in this guide, I was able to reduce the temperature from more than 70°C to just 60°C. Unfortunately, I still couldn't get it to run reliably at Radeon 9800XT clock speeds.

I only managed to clock the card up to 390MHz for both core and memory. Anything higher than that resulted in image artifacts. Even with the AMD cooler modded onto the card, its PCB still remained hot to touch.

Another obvious change after flashing the Radeon 9800XT BIOS is a new tab in the ATI control panel. It was the OVERDRIVE tab!

This feature can only be found in the Radeon 9600XT and 9800XT cards. OVERDRIVE is basically a dynamic overclocking utility provided by ATI. It dynamically overclocks your card based on the GPU's temperature, as read by the onboard thermal diode. The temperature readings can be monitored in the OVERDRIVE tab.