Introduction and AMD Rigs
Since AMD announced its Mantle initiative in September last year, we’ve been excitedly hypothesising what it could really mean for AMD, its graphics cards, our processors and PC gaming in general. And now it’s finally here – with a beta release of Catalyst and a couple of Mantle-enabled apps – giving us an insight into what it’s actually going to do for our machines.
Thankfully, one of those Mantle-enabled apps happens to be a favourite, Battlefield 4. Therefore, we’ve finally got a tangible idea of what performance boost AMD’s Mantle API is going to give our rigs in a real gaming environment. DICE has been instrumental in getting Mantle up to speed; without its support, Mantle would be just another tantalising tech demo.
So, what is Mantle? it’s essentially a new graphics application programming interface (API) to replace Microsoft’s DirectX for AMD GCN cards in compatible games. "When we originally approached Mantle – and I was there the day we decided to do this – we thought: ‘y’know, we just want to make games faster.’ Here’s a way to give developers access as close as possible to the metal – like they can do on the consoles," AMD’s Neal Robison told us at CES.
Without all the layers of legacy programming and cross-vendor support in DirectX, Mantle ensures there is little to get in the way of programmers and the hardware for which they are writing code. The interesting thing is that, despite being a graphics API, it’s the CPU that’s set to feel the real benefit. DirectX introduced lots of processor overhead into games and where they’re CPU-bound Mantle will deliver a pretty decent performance boost. But just how much? We’ve taken a look at three different motherboard/processor combinations with a high-end and more mainstream GPU to see what Mantle can do for you.
AMD APU: AMD A10-7850K
The first system we’ve looked is built around AMD’s new APU, the A10-7850K. Despite being its latest silicon, the APU doesn’t make a particularly effective basis for a gaming PC. Using the same R9 290 graphics card, the AMD APU is almost 45 per cent slower in Battlefield 4 compared with the similarly-priced Intel Core i5-4570 CPU. However, as soon as you throw Mantle into the mix, the lower CPU overhead closes the gap between the Intel and AMD processors.
While running both machines on Ultra at 1080p in Battlefield 4, the Intel chip still retains a lead, but it’s slashed in half. Now the APU is only around 20 per cent behind the straight CPU silicon of the Core i5. At 1080p, this Kaveri system saw the biggest boost in gaming performance. At Ultra settings, it gets some 36 per cent extra frame rate performance, and at High it gets 45 per cent. For a software update that’s a great return. The Star Swarm benchmark also displays some huge improvement gains for Mantle over the DirectX codepath.
We also saw some improvements at both 2560 x 1600 and 4K resolutions with Kaveri, though that was only 10 per cent at best. Still, it shows that even when the system is primarily GPU bound it can get a performance boost when it’s kitted out with the right card. With the wrong card, though, things aren’t so rosy. When the lower-end HD 7870 card is used, the system is GPU bound even at 1080p in Battlefield 4. In fact, it actually negatively impacts performance rather than simply not giving the system a boost.
Performance on the AMD Radeon R9 290 – 1080p (FPS, higher is better)
Battlefield 4 – Mantle (min/avg): 23/68Battlefield 4 – DirectX (min/avg): 28/50StarSwarm – Mantle: 50StarSwarm – DirectX: 26
Performance on the AMD Radeon HD 7870 – 1080p (FPS, higher is better)
Battlefield 4 Ultra – Mantle (min/avg): 9/43Battlefield 4 Ultra – DirectX (min/avg): 25/45StarSwarm – Mantle: 40StarSwarm – DirectX: 24
AMD Gamer: AMD FX-8350
We were hoping to see the benefits of Mantle giving heavily multi-threaded processors their time in the gaming sunshine with the top-end AMD FX CPU. It is, after all, the cheapest CPU to offer a full eight threads. Sadly, even with Mantle, those eight threads aren’t able to push performance past the mighty Intel chips. Still, the FX-8350 is incredibly consistent, even if it can’t post the sort of percentage improvements that the A10-7850K offers.
Using the same Radeon R9 290 card, the FX-8350 sees at least a 20 per cent frame rate boost at both Ultra and High settings in Battlefield 4. And that’s counting both 1080p and 2560 x 1600 resolutions. This FX CPU displays both the best and worst of Mantle. The Hawaii powered 290 brings the FX up to almost the same sort of levels of gaming performance as the Intel chip – at 1080p, 1600p and 4K the FX-8350 offers average frame rates only slightly behind Intel.
When you bring the HD 7870 into the equation, however, the gaming performance becomes a disaster – at best, Mantle offers a 10 per cent degradation in BF4 frame rates. The GCN cores of the Pitcairn GPU simply don’t sit well with the Mantle update in Battlefield 4. Yet Star Swarm shows that it’s just a problem with the BF4 code. As you can see, the Star Swarm benchmark can still deliver a 63 per cent performance boost even with the HD 7870. With the R9 290 that increase is a pretty startling 104 per cent, though it is coming from a pretty lowly start point.
Performance on the AMD Radeon R9 290 – 1080p (FPS, higher is better)
Battlefield 4 – Mantle (min/avg): 26/78Battlefield 4 – DirectX (min/avg): 40/64StarSwarm – Mantle: 47StarSwarm – DirectX: 23
Performance on the AMD Radeon HD 7870 – 1080p (FPS, higher is better)
Battlefield 4 Ultra – Mantle (min/avg): 9/37Battlefield 4 Ultra – DirectX (min/avg): 32/50StarSwarm – Mantle: 39StarSwarm – DirectX: 24
Intel Gamer rig and conclusion
Intel Gamer: Intel Core i5-4570
The Intel processor ironically seems to benefit the most from the introduction of the Mantle API. While the AMD processors get impressive performance boosts – therefore bringing them closer to the gaming pace of the Intel chips – those blue CPUs also get a lift.
This Core i5 is actually able to squeeze more performance from its partnership with the otherwise struggling HD 7870, and gets a hefty boost from the R9 290 pairing as well. The interesting thing for Intel is that it doesn’t suffer from the same collapse in minimum frame rates that befalls AMD processors. We put the shaky performance down to the immature beta API still not being quite finished. While the i5′s frame rates get smoother across the board, AMD frame rates stutter more and more.
In general, we don’t see as much of a percentage performance gain as we do with the AMD processors, but that’s mostly because the DirectX starting point has far higher average frame rates anyway. Where game engines are CPU bound, Intel chips outperform the competition.
When you bring Mantle into play, the gap in performance may often be cut but the Intel chips still come out on top. Nonetheless, where games are mostly GPU bound, Mantle ensures that the AMD processors aren’t left behind. That is highlighted best in the 4K BF4 tests. There is almost no boost on Ultra, but on High both AMD and Intel saw the same boost and hit the same average frame rates.
Performance on the AMD Radeon R9 290 – 1080p (FPS, higher is better)
Battlefield 4 – Mantle (min/avg): 55/82Battlefield 4 – DirectX (min/avg): 45/72StarSwarm – Mantle: 57StarSwarm – DirectX: 38
Performance on the AMD Radeon HD 7870 – 1080p (FPS, higher is better)
Battlefield 4 Ultra – Mantle (min/avg): 19/58Battlefield 4 Ultra – DirectX (min/avg): 31/51StarSwarm – Mantle: 42StarSwarm – DirectX: 32
Conclusion: Good news for Intel
Unfortunately for all you AMD CPU fans, Mantle isn’t the magic bullet to give its processors a boost over the Intel-shaped competition. While Mantle does allow the FX processors to get a lot closer to the performance of Intel CPUs, 4th-gen Core chips get a boost of their own. The new API isn’t going to change Intel’s desktop dominance of the gaming market.
After looking at the performance boosts that Mantle API offers the processor landscape, we think we might have more of a handle on AMD’s strategy. When it was announced that AMD wasn’t looking to roll out the Steamroller core update to its FX line of CPUs and was limiting it to the Kaveri APUs, we questioned that decision. Now it seems clearer: AMD has essentially given up on the straight CPU. That’s not as defeatist a line as it might at first sound.
Given that most gamers would rather have an Intel CPU at the heart of their rigs, has AMD decided that it needs to focus on making sure that those gamers are pairing their Intel silicon with an AMD card? Forget trying to get them to buy a weaker FX chip, let’s just stop them buying an Nvidia GPU to go with their Intel CPU. With Mantle and an Intel CPU, you get an increase in average frame rates as well as in minimum frame rates.
That means your Mantle enabled game is not only quicker on an Intel CPU/AMD GPU PC, but smoother too. It’s the same situation in the Battlefield 4 test as it is in the Star Swarm benchmark. Star Swarm proves that when an engine is coded with Mantle in mind from its early development, the performance boost is more consistent across different platforms.
In Battlefield 4, the HD 7870 is a nightmare for the AMD setups, while in Star Swarm both R9 290 and HD 7870 get the same sort of backing. This is all good news for us PC gamers, especially those of us who are already sitting on an AMD GCN-based card. It’s true that at present, the Hawaii cards get the best of Mantle, but in the future, the whole stack should get a decent boost from Mantle compatible games – and that’s got to be a little worrisome for Nvidia.
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