Battlefield 4: RAM Issues And Driver Updates
As mentioned, we let AMD know about our Mantle issues under Battlefield 4, and was told that the game currently suffers from an issue that results in lower performance on cards with less than 4 GB of memory. In order to test this issue, we were sent an MSI Radeon R9 270X with 4 GB of GDDR5. Does the extra memory alleviate our observed problem?
While we don't see the performance penalty that Mantle caused previously, there's no perceptible advantage, either.
Once again, the frame time variance is exceptionally low on average, and the occasional spikes make little difference.
For now, it appears that on-board memory isn't the only limiting factor. At least in Battlefield 4, Mantle demonstrates an advantage over DirectX on high-end cards with 4 GB of memory. The extra GDDR5 doesn't appear to help a Radeon R9 270X under the API.
Battlefield 4 (June 3 Update) And Catalyst 14.6 Beta Release Candidate 2
This is one of the most benchmark-intensive articles I've ever written, involving multiple graphics cards tested across multiple platforms. I began the project back when Catalyst 14.4 Beta was the newest driver available, but used Catalyst 14.3 Beta because there were instances of the 14.4 driver penalizing performance.
Once testing was complete, I spent a lot of time doing additional research. I discussed the numbers with AMD, which led to 4 GB corner case benchmarking. I did more homework on APIs, and Chris Angelini spent some time with AMD's Richard Huddy in Bakersfield. To make a long story short, enough time passed that Battlefield 4 received an update on June 3rd, and AMD released its Catalyst 14.6 Beta driver.
I needed to make sure that my Mantle-based performance data was still relevant, so I ran a few tests with the latest updates and found that, in Battlefield 4, performance under Mantle improved on video cards with less than 4 GB of memory. The bad news is that, while the gap gets smaller, AMD's API is still a tad slower with a less consistent frame rate than DirectX 11. Even though the gap is much closer, Mantle doesn't offer an advantage in anything less than a Radeon R9 290.
The bottom line is that Radeon cards with less than 4 GB of memory still do not benefit from a performance advantage in Battlefield 4 under Mantle. But with the newest driver and game patch, that hit is smaller than our numbers with the 14.3 Beta package. Its an encouraging development, which speaks to the work AMD and DICE are putting into the API. But it also shows us how much effort is required. We'd hope that Battlefield 4 would run faster under Mantle, regardless of the card installed and its on-board graphics memory capacity.