iPad A8x chip vs A7

Samtb

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Original poster
Jan 6, 2013
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Why was there never an A7X? Did they use the same A7 in iphone 5S in the iPad Air? And how does this compare with A8 and A8X?
 

TheDeviceUser

macrumors 6502a
Jul 20, 2014
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U.K
Why was there never an A7X? Did they use the same A7 in iphone 5S in the iPad Air? And how does this compare with A8 and A8X?
My guess, Apple thought A7 was enough to power the Retina Display, although it wasn't. Some of the graphics on the iPad Air are pretty choppy, especially Siri. It was the same as the iPhone 5s A7 only clocked a little faster. Graphics are 2.4x faster and CPU tasks are 50% faster compared to the A7.
 

highlightshadow

macrumors regular
Oct 11, 2012
182
0
Have high hopes for the A8X .... i bought retina ipad mini last year and sent it back straight away cos it was clear the A7 wasn't quite man enough for the new display

Given the iPhone6+ suffers a little of the same this year with the A8 but not much then i figure the A8X should nail it ... esp if they do include more ram + higher clock speed.
 

scupking

macrumors 6502a
Dec 14, 2010
620
194
The a7 is plenty fast enough for the retina display. Just think the ipad three was on the a5x with the same display. The a8x will be overpowered (not that its a bad thing)!
 

s2mikey

macrumors 68020
Sep 23, 2013
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Upstate, NY
The A8X specs out nicer than the A7 but I have seen that in real world usage that the end user may not perceive all of the benefits. It depends on the app, what they are doing and other factors. Hey, upgrades are upgrades though and we'll take them.

I'm just saying that when something has a spec that claims its xxx% faster that doesn't mean that performance is always tangible.
 

BMcCoy

macrumors 68000
Jun 24, 2010
1,600
3,169
The iPad Air uses a different version of the A7 chip.. not just clocked slightly faster.

The first version of the A7 was a package-on-package (PoP), with stacked RAM. However the newer version in the iPad Air used chip-on-board mounting, immediately adjacent DRAM, and is covered by a metallic heat spreader.

This made it more similar A5X and A6X chips. They could have easily called it the A7X.
 

Ledgem

macrumors 68000
Jan 18, 2008
1,871
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Hawaii, USA
Have high hopes for the A8X .... i bought retina ipad mini last year and sent it back straight away cos it was clear the A7 wasn't quite man enough for the new display
The resolution used on the retina iPad mini was first introduced with the iPad 3, which used an A5X (an A5, but with additional graphical cores). If you go by the benchmark numbers, the A7 has about triple the performance of the A5.

The iPad 3 is regarded as being underpowered, but it didn't suffer any stuttering or graphical issues at the time. Some of those visual glitches appeared when iOS 7 was released, but later versions of iOS 7 smoothed them out. Now they're back with iOS 8. What you're seeing and experiencing is a software problem, not anything related to hardware being underpowered to drive the display.
 
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Samtb

macrumors 65816
Original poster
Jan 6, 2013
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The resolution used on the retina iPad mini was first introduced with the iPad 3, which used an A5X (an A5, but with additional graphical cores). If you go by the benchmark numbers, the A7 has about triple the performance of the A5.

The iPad 3 is regarded as being underpowered, but it didn't suffer any stuttering or graphical issues at the time. Some of those visual glitches appeared when iOS 7 was released, but later versions of iOS 7 smoothed them out. Now they're back with iOS 8. What you're seeing and experiencing is a software problem, not anything related to hardware being underpowered to drive the display.
Do you think the air was underpowered?
 

Rodster

macrumors 68040
May 15, 2007
3,178
6
The iPad 3 is regarded as being underpowered, but it didn't suffer any stuttering or graphical issues at the time. Some of those visual glitches appeared when iOS 7 was released, but later versions of iOS 7 smoothed them out. Now they're back with iOS 8. What you're seeing and experiencing is a software problem, not anything related to hardware being underpowered to drive the display.
Ding..ding..ding, we have a winner. It's not the hardware but the OS.
 

Shuri

macrumors 6502
Nov 23, 2011
330
0
Do you think the air was underpowered?
Ran the Zen Garden Metal Demo on an iPad Air: Can't see how anyone can say this thing is underpowered. iOS 7 had it's problems, true, but as already stated: Software problems.
 

Chundles

macrumors G4
Jul 4, 2005
11,978
422
The iPad Air uses a different version of the A7 chip.. not just clocked slightly faster.

The first version of the A7 was a package-on-package (PoP), with stacked RAM. However the newer version in the iPad Air used chip-on-board mounting, immediately adjacent DRAM, and is covered by a metallic heat spreader.

This made it more similar A5X and A6X chips. They could have easily called it the A7X.
Nah, the "X" nomenclature was reserved for the chips with quad-core graphics. A5 had dual core, A5X had quad, A6 had triple-core, A6X had quad.

The A7 in the iPad had a different layout but the performance difference was equal to the 0.1GHz extra speed it had. There was no change in real-world performance.
 

Poochi

macrumors 6502a
Jul 30, 2010
875
236
Toronto
If my Air only have an A7 chip instead of A7X then I'm disappointed. Time to upgrade to Air 2
A7 is fine. You can think it as A7onsteroid if compared to iPhone 5S's A7.

If you can't really tell the difference then you are buying into Apple's marketing.

A9 in less than 1 year will be much much better, but you can't really feel it.
 

Appl3FTW

macrumors 603
Nov 15, 2012
5,392
1,024
The A7 was a beast of a chip. 5s didn't even utilize its full potential. So for the iPad series its still great.
 

cfedu

Suspended
Mar 8, 2009
1,166
1,566
Toronto
The iPad Air uses a different version of the A7 chip.. not just clocked slightly faster.

The first version of the A7 was a package-on-package (PoP), with stacked RAM. However the newer version in the iPad Air used chip-on-board mounting, immediately adjacent DRAM, and is covered by a metallic heat spreader.

This made it more similar A5X and A6X chips. They could have easily called it the A7X.
Not at all
 

Ledgem

macrumors 68000
Jan 18, 2008
1,871
710
Hawaii, USA
So the x notation at the end is just marketing?
The "X" designation has thus far been used by Apple to indicate that there are additional graphical cores compared to the "non-X" version. The iPad Air had an A7 instead of an A7X because even though the clock speed was different, it had the same number of graphical cores as the A7 in the iPad Mini and the A7 in the iPhone 5S.
 

smiddlehurst

macrumors 65816
Jun 5, 2007
1,226
22
The "X" designation has thus far been used by Apple to indicate that there are additional graphical cores compared to the "non-X" version. The iPad Air had an A7 instead of an A7X because even though the clock speed was different, it had the same number of graphical cores as the A7 in the iPad Mini and the A7 in the iPhone 5S.
Actually that's not entirely accurate. Yes, there were more GPU cores compared to the standard A5 and A6 but it also had a 128 bit memory interface compared to the 64 bit interface of their phone brethren. Half of that extra bandwidth was reserved for the GPU. With the A7 Apple changed direction and went with a 64 bit interface for all devices and an integrated 4MB of SRAM to act as a cache.

What's going to be really interesting is seeing how Apple have spent that extra 1 billion transistors they have over the A8. What follows is entirely speculation of course but considering the 2.5x GPU increase over the A7 I'm assuming they've gone for a 6 core GPU but that's unlikely to take up all that space. A bigger cache? Back to 128 bit memory interfaces? Who knows (well, Apple does of course but they ain't saying) but it's going to be interesting finding out.

That said I do think it's worth considering the bigger picture. The A7 was, frankly, massively over-powered for the iPhone 5s and while the A8 is a better match in the 6+ it still seems like overkill in the 6. Certainly an A8 could have driven the Air 2 without issues so... why build the A8X? It gives them a way to differentiate the Air 2 from other A8 devices of course but with the iPad Mini's staying on A7 is it necessary when screen size would likely be the defining factor? Will the A8X show up in other products before the A9 rolls out next September?
 

rotation

macrumors member
Oct 16, 2014
80
0
Los Angeles
Actually that's not entirely accurate. Yes, there were more GPU cores compared to the standard A5 and A6 but it also had a 128 bit memory interface compared to the 64 bit interface of their phone brethren. Half of that extra bandwidth was reserved for the GPU. With the A7 Apple changed direction and went with a 64 bit interface for all devices and an integrated 4MB of SRAM to act as a cache.

What's going to be really interesting is seeing how Apple have spent that extra 1 billion transistors they have over the A8. What follows is entirely speculation of course but considering the 2.5x GPU increase over the A7 I'm assuming they've gone for a 6 core GPU but that's unlikely to take up all that space. A bigger cache? Back to 128 bit memory interfaces? Who knows (well, Apple does of course but they ain't saying) but it's going to be interesting finding out.

That said I do think it's worth considering the bigger picture. The A7 was, frankly, massively over-powered for the iPhone 5s and while the A8 is a better match in the 6+ it still seems like overkill in the 6. Certainly an A8 could have driven the Air 2 without issues so... why build the A8X? It gives them a way to differentiate the Air 2 from other A8 devices of course but with the iPad Mini's staying on A7 is it necessary when screen size would likely be the defining factor? Will the A8X show up in other products before the A9 rolls out next September?

I would put a good bet on A8 having the same Dual core design but using a much wider memory interface and a 6 or 8 cluster PowerVR GPU.


40% CPU over A7, with IPC taken into account (roughly 15% gain from A7), would mean the A8X is clocked around 1.7Ghz.

2.5X GPU would require at least a 6 cluster PowerVR 6XT, and double the memory bandwidth to feed the ROPs.



My educated guesses.
 

Donka

macrumors 68030
May 3, 2011
2,782
1,399
Scotland
If the A7 was under powered for iPad retina display, why are Apple sticking with it for the mini 3? If it wasn't up to the task, they would have given the mini 3 an A8 and kept the A8X for the Air to delineate the two models.
 

rotation

macrumors member
Oct 16, 2014
80
0
Los Angeles
If the A7 was under powered for iPad retina display, why are Apple sticking with it for the mini 3? If it wasn't up to the task, they would have given the mini 3 an A8 and kept the A8X for the Air to delineate the two models.
A7 is not at all underpowered. It still floors every other SoC out there except A8 in browsing. Its graphics are second only to the A8 and Adreno420 (Note 4).




They stuck it in the mini 3 because it's more than adequate performance wise, and it's cheap to make as it's on 28nm .
 
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