AMD Responds With A Driver Fix
We were working toward the publication of our data when AMD finally got back to us regarding our concerns.
According to an AMD representative, the company was surprised to find that our results were easily replicated. The problem was tracked back to something that could be fixed in the driver. So, regardless of whether it's a hardware or software issue, a workaround is purportedly possible. AMD has not been forthcoming about the details, but apparently our observed results are caused by an anisotropic filtering change implemented for the Radeon HD 7800 launch in order to get rid of shimmering in a filtering test. The representative claims that the driver team found the source of the issue and was able to fix it without sacrificing filtering quality or performance.
Just prior to publication, AMD provided the following official statement:
"For our Southern Island product family launch we picked a set of settings that we tested in several scenarios for image quality and found that those specific settings were providing the best overall quality. When you pointed out these issues in some games around texture quality, we went back and found one specific setting that was causing the described texture blurriness. This has now been removed and the quality of textures should be as intended, with performance unchanged. These settings will be adjusted accordingly in the 12.4 April Catalyst release, later this month."
With a pre-release version of the fixed driver in hand, we went on to see if AMD's solution solved our problem without negatively impacting anything else. First, let’s look at the texture quality results:
Excellent. The new driver fixes the texture blurriness issues. And, at default settings, the Radeon HD 7870 series textures appear at least as crisp as the Radeon HD 6970. This is very good news indeed.
But now that we see the problem was addressed, we must ask if performance takes a subsequent hit? Do frame rates at default settings drop to what they were at the High Quality slider position in the old driver?
Despite the obviously higher image quality provided by the fixed driver, resulting performance is almost identical and well within a margin of error.
The frame rate differences in Metro 2033 are also insignificant.
The same story applies to Crysis 2.
Thankfully, performance seems unaffected by the fixed driver and accompanying image quality improvement.
Finally, since AMD claims that its problem was the result of an anisotropic filtering technique, we thought it would be a good idea to compare the output. Does AF suffer because of the driver fix?
Anisotropic filtering is identical between the Radeon HD 7800 launch driver and the beta driver AMD sent to us. The 3DCenter filter tester appears to produce the same output on the Radeon HD 7870 with either driver, while the Radeon HD 6970 demonstrates inferior filtering compared to the 7000 series. Even when playing back video of the tunnel test, we couldn't notice a difference in shimmering between the launch and fixed driver.