The iPad Air Review
by Anand Lal Shimpi on October 29, 2013 9:00 PM ESTGPU Performance
Since the iPad Air uses the same A7 silicon as the iPhone 5s, it also uses the same on-die GPU as the 5s: IMG’s PowerVR G6430. This is a 4-cluster configuration of IMG’s latest graphics hardware, running at some relatively high frequency. I already went into some detail on the G6430 in our 5s review so I won’t rehash that here, but we’re basically looking at a shift to a more efficient scalar architecture.
I still don’t have confirmations of clock speeds, but I believe we’re looking at a max GPU clock of around 450MHz. As you’ll see from the results below, there’s a small difference in performance between the iPad Air and iPhone 5s in terms of peak GPU performance - implying very similar clocks. The difference is the iPad Air should be able to sustain its max frequency longer than the iPhone 5s can.
Mobile SoC GPU Comparison | ||||||||||||
PowerVR SGX 554MP4 | PowerVR G6430 | PowerVR G6430 | ||||||||||
Used In | iPad 4 | iPhone 5s | iPad Air | |||||||||
SIMD Name | USSE2 | USC | USC | |||||||||
# of SIMDs | 32 | 4 | 4 | |||||||||
MADs per SIMD | 4 | 32 | 32 | |||||||||
Total MADs | 128 | 128 | 128 | |||||||||
GFLOPS @ 300MHz | 76.8 GFLOPS | 76.8 GFLOPS | 76.8 GFLOPS | |||||||||
GFLOPS as Shipping | 68.1 GFLOPS (?) | 115.2 GFLOPS | 115.2 GFLOPS |
Since we’re talking about an A7 here and not an X-series SoC, there’s still only a 64-bit wide memory interface. As memory bandwidth is a key enabler of GPU performance I was curious to see how GPU performance compared to the outgoing iPad 4 with its much wider memory interface. Do keep in mind that the A7 does include a large system cache on-die, which can help improve effective memory bandwidth.
GFXBench 2.7
We'll start our GPU performance analysis with a look at low level results using GFXBench/GLBenchmark 2.7. The low level tests, particularly the offscreen ones, should give us some idea as to whether or not there's any increase in GPU frequency for the iPad Air vs. iPhone 5s implementations of A7.
Looking at the fill rate results, there's a 4.5% increase in performance compared to the iPhone 5s. That could be the magnitude of clock increase that we're seeing between A7s. Apple could very well be relying on more thermal headroom in the iPad Air to provide any real world GPU performance advantages over the iPhone 5s.
We see an even smaller gap between the Air and 5s in the triangle throughput tests (2.9%). There doesn't seem to be any substantial difference in GPU frequency between A7 implementations here. The regression in triangle rate performance compared to the iPad 4 is explained by differences in how Series 6 and Series 5XT GPUs scale in width. Whereas 5XT replicated nearly the entire GPU for "multi-core" versions, multi-cluster versions of Rogue only replicate at the shader array. The result? We don't see the same sort of peak triangle setup scaling we did back on multi-core 5XT parts. I'm not sure I'm particularly happy with the magnitude of the regression here, but I haven't seen any real world cases where it matters yet.
Next up are the game simulation tests. We'll start with the more strenuous of the two: T-Rex HD.
Here we get closer to Apple's claims of a 2x increase in performance. The iPad Air delivers 75% more performance than the iPad 4 in this test. Once again the iPhone 5s pulls ahead but that's because the onscreen tests render at display resolution, which is lower on the 5s.
Offscreen performance sees similar scaling: ~69% better performance compared to the iPad 4.
3DMark
We're once again running 3DMark's newest Unlimited mode which does its best to run independently of v-sync and at a standard resolution across all devices. I've also included 3DMark Extreme results below that feature a few more comparison points.
The overall Ice Storm scores show a 36% improvement in performance over the iPad 4 and an 8% increase compared to the iPhone 5s. Given the CPU frequency advantage of the A7 in the Air vs. the iPhone 5s, I'm guessing that's why we're seeing the performance gap we are here.
If we focus exclusively on the GPU tests (which themselves are still CPU bound), the iPad Air's performance advantage over the iPad 4 grows to over 60%.
I'm still not entirely sure what's going on with the 3DMark Physics test, but we've seen this two reviews in a row now where Cyclone showed no performance increase at all compared to Swift despite this being largely a CPU test.
Basemark X
Basemark X is a new addition to our mobile GPU benchmark suite. There are no low level tests here, just some game simulation tests run at both onscreen (device resolution) and offscreen (1080p, no vsync) settings. The scene complexity is far closer to GLBenchmark 2.7 than the new 3DMark Ice Storm benchmark, so frame rates are pretty low.
I'm still having random issues with Basemark X reliably running both on and offscreen tests on iOS 7. Unfortunately I could only get onscreen results for the iPad Air, which came in at 46% faster than the iPad 4. Note the iPad mini and iPhone 5s benefit from having lower native resolutions here, which is why they perform so well.
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dishayu - Wednesday, October 30, 2013 - link
I agree on one tiny point with you. The shortcomings of a device need to be highlighted when it comes out... NOT when the successor is launched. And I've read AnandTech long enough to know that this is not just a problem with Apple reviews. This is the problem with all reviews... Android, PC and storage reviews and so on... As soon as a refresh/next gen product is launched, the previous gen suddenly develops issues/shortcomings. Don't get me wrong, their reviews are still the best and more in-depth than rest of the internet combined, but they seriously need to address this little issue.BlakKW - Wednesday, October 30, 2013 - link
pretty valid observationerrorr - Wednesday, October 30, 2013 - link
I'm not sure people really understand the shortcomings when a product comes out. I appreciate when Anand or Brian use a product for a while and their insights are far superior, but initial impressions on a review are still subject to change gradually.KoolAidMan1 - Wednesday, October 30, 2013 - link
How dare a company improve the performance of its productsandroticus - Tuesday, October 29, 2013 - link
When is that MacBook Pro review coming???? :)FwFred - Wednesday, October 30, 2013 - link
Yep, much more excited about that from a device standpoint, though the A7 investigaton was interesting.tipoo - Tuesday, October 29, 2013 - link
Woah, the Surface charges fast.MarcSP - Tuesday, October 29, 2013 - link
Yeah. Ii is not just a little bit, it is half the time! Of course the review somehow tries not to make it look as a really negative thing or at least something to really improve for the next iPad. In fact it says it is GOOD, compared to ipad 3 and 4, that were ludicrously slow in charging.Of course, in the Surface 2 review there was no mention at all of this fast charging, only of the "average battery life".
And BTW I think battery life in Surface 2 should be retested. It is extremely weird that it got less web browsing time than Surface 1 (and that this discrepancy was not even mentioned in the review). If possible use a different Surface 2 device, just in case it had some problem.
YuLeven - Wednesday, October 30, 2013 - link
And other sites got 14 hours of battery when testing the Surface 2.basroil - Tuesday, October 29, 2013 - link
" The iPad Air crashed a couple of times on me (3 times total during the past week), but no where near as much as earlier devices running iOS 7.0.1. "Not a single W8 device I own has ever crashed from system memory issues (one crashes because the GPU was overclocked too hard and graphics memory suffered from it, but that's hardware failure not software)