We have just received confirmation from AMD that some ATI Radeon HD 4830 boards have only 560 stream processors enabled, instead of the 640 that there should be. A limited number of these have made it into the channel.

It's something we'd been scratching our heads over for a few days now, after finding that the performance data we'd collected didn't make a lot of sense. We've heard various stories from AMD, from it being a "known issue" to there being problems with the application calculating the number of stream processors.

The latter statement was one we frankly didn't believe because our own calculations based on theoretical performance just didn't add up at all. On that note, I guess it's good to know that AMD has finally come out and admitted that there was a problem with the samples, following what essentially amounted to a "no comment" earlier in the week.

Here's the quote:

" AMD has identified that, in addition to reference samples of the ATI Radeon™ HD 4830 boards sent to media with a pre-production BIOS potentially impacting the card’s performance, a very limited number of ATI Radeon™ HD 4830 boards were released to market with the same pre-production BIOS. This is in no way hardware related, and an updated BIOS fully resolves the performance limitation.

Through consultations with AMD board partners, it has been determined with a high degree of certainty that fewer than 400 ATI Radeon™ HD 4830 boards from one AMD board partner, HIS, have reached the market with the pre-production BIOS incorrectly provided by AMD. As only a small number of HIS-branded ATI Radeon™ HD 4830 cards are impacted, we ask any customers that purchased an HIS-branded ATI Radeon™ HD 4830 to test the board using the GPU-Z utility (available at http://www.techpowerup.com/gpuz). If the GPU-Z utility reports fewer than 640 shaders, please visit the HIS website for information on how to update the card BIOS via a downloadable install utility."