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ATI RADEON 9800 SE 256bit

The story of ATI RADEON 9800 SE based graphics cards is very similar to the story of RADEON 9700 and their cut-down modifications, RADEON 9500. Although this time, it is not R300, but R350, which loses some of its functional units. So the resulting graphics chip has not a different numeric index like in case of RADEON 9700 and 9500, but the same 9800 index though with the “SE” suffix in the end.

There are only three differences between the RADEON 9800 SE and the fully-fledged RADEON 9800/9800 PRO: two grave differences and one trifling difference:

  1. Unlike RADEON 9800, RADEON 9800 SE features 4 pixel pipelines instead of 8. The functionality of the existing pixel pipelines and the number of vertex pipelines remained the same.
  2. Unlike “fully-fledged” graphics chip modifications, RADEON 9800 SE has HyperZ III unit disabled.
  3. RADEON 9800 SE can work at lower frequencies than RADEON 9800 does.

In fact, RADEON 9800 SE is based on the chips, which failed the test for “fully-fledged” chips, but are perfectly fit for work with 4 disabled pixel pipelines and disabled HyperZ III. I would like to point out that physically functional chip units are not disabled in this case. Instead they change the DeviceID of the graphics processor, and when the graphics card driver sees the RADEON 9800 SE DeviceID, it doesn’t activate half of the available pixel pipelines and HyperZ. When we change the DeviceID of the chip on the hardware or software level, so that it again indicates RADEON 9800/9800 PRO, the driver starts using the graphics processor potential to the full extent.

Of course, when we transform RADEON 9800 SE into RADEON 9800 far not all the graphics chips remain operational. In case of a failure, you may notice some visual artifacts caused by incorrect HyperZ III functioning. Sometimes, they may also result from the deficiencies of the previously disabled pixel pipelines. “Successful” modification implies that the bugs discovered during the quality tests on the fab are either insignificant, or have no effect on the image quality, or pop up in some rare exotic conditions.

RADEON 9800 SE based graphics cards are positioned as low-cost versions of the top RADEON 9800 and follow the reference design of RADEON 9700 and 9500 PRO instead of that of the RADEON 9800/9800 PRO based solutions. Therefore, there are two major types of graphics cards known as RADEON 9800 SE: those based on RADEON 9700 reference design and equipped with 256bit memory bus and those on RADEON 9500 PRO reference design equipped with 128bit memory bus.

The graphics card modification with 256bit bus will be represented by a Sapphire solution:

Actually the graphics processor is the only thing that distinguishes this graphics card from RADEON 9700. all the other elements of the card remained absolutely the same: even the cooler is the same as those used on RADEON 9700/9700 PRO based graphics accelerators.

The card is equipped with 128MB of DDR SDRAM from Infineon with 3ns cycle time (Infineon HYB25D128323C-3.3). The graphics processor works at 325MHz and the graphics memory – at 550MHz frequency.

To perform the necessary modifications I used a special PatchScript utility included into the Rivatuner package and after that the card worked flawlessly as a RADEON 9800. However, its overclocking potential was far from impressive: the graphics chip and memory managed to retain stability at only 360MHz and 600MHz respectively.

These pretty low overclocking results can partially be explained by the fact that the power voltage of the graphics processor on this card equals the nominal voltage of the RADEON 9700, since the card is designed according to the RADEON 9700 reference layout. And this value is far from the acceptable voltage for RADEON 9800, because it equals only 1.54V instead of the required 1.7V.

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