What does the "watered-down" i5 in Macbook air mean?

tonynz

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Original poster
Oct 24, 2008
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Hi all,

I have a Macbook Air and I've been told that the i5 is pretty much watered down.

What does this mean? Does it still perform on par with a normal i5 that I have on my desktop at work?

Thanks
 

Ivan P

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Jan 17, 2008
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Due to the thin form factor of the MacBook Air, they have to use smaller chips to avoid overheating, etc. As a result, the base 11" MacBook Air, for example, has a 1.6GHz Core i5 processor, compared to the 2.3GHz Core i5 found in the base 13" MacBook Pro. In the end it's just slight performance differences. Feasibly the air runs 'slower'.
 
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Xikum

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Oct 19, 2011
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Desktop components on a whole take up alot more power than their laptop counterparts. Laptops use "mobility" parts, which you can tell by the fact the model name has an "M" after it (e.g. i5 2577M). These are essentially slower than their desktop counterparts, which would generate far too much heat and take up too much power to ever be put in a laptop.

The correct name for processors such as the one in the MacBook Air is ULV; ultra low voltage.
 
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LordVic

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Sep 7, 2011
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this "watered down" term is a misnomer.

The cpu's in the Air aren't "less powerful" than their larger counterparts.

They have a built in "throttling" for both reducing heat created, and increasing battery life.

Normal state of this CPU (for example i5-2467M) is 1.6GHZ. However, when under heavy enoguh load, and I believe while plugged in, it will clock itself up to 2.3Ghz, which i believe is on par for the similarly modeled pro.

This is not "watering down" the CPU. But a power conservation method used in these ultra books

A little table of real clock speed, versus the throttled
CPU - Lowpower mode - High power mode
i5-2467M - 1.6ghz - 2.3ghz
i5-2557M - 1.7ghz - 2.7ghz
i7-2677M - 1.8ghz - 2.9ghz
 
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Stewart21

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Dec 9, 2011
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South Yorkshire
Hi all,

I have a Macbook Air and I've been told that the i5 is pretty much watered down.

What does this mean? Does it still perform on par with a normal i5 that I have on my desktop at work?

Thanks
These Core i5 and Core i7 processors work differently to previous generations of processors. The raw numbers for processor speed mean little these days.

This article at macworld explains it very well, go here for the full review of the MBA http://www.macworld.com/article/161434/2011/08/macbook_air_2011.html

but here's a quote from the article

One way the Core i5 chips manage to be faster than Core 2 Duos at the same speed is because the Core i5 and i7 have access to two clever Intel tricks: Hyper-threading and Turbo Boost. Hyper-threading means that while these chips have two processor cores, they appear to the operating system as if they've got four cores. This trick allows the processor to run more efficiently when it comes to heavy-duty number crunching. In many ways, Turbo Boost produces the opposite effect: When only one processor core is being tasked, the chip can shut down one core and crank up its clock speed, allowing it to run inefficient software at higher speeds than an older chip could.

Stewart
 
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KPOM

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Oct 23, 2010
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The chip is pretty much the same. It just runs a bit slower while performing normal tasks in order to conserve power. The 1.6GHz i5 can boost up to 2.0GHz when running both cores. The 1.7GHz model can go up to 2.4GHz, and the 1.8GHz i7 can go as fast as 2.6GHz. By contrast, the 2.4GHz i5 in the base 13" MacBook Pro can boost both cores to 2.7GHz. Thus, while the Pro runs at a higher base speed, when both are running at full throttle there isn't as much difference.

The difference gets bigger when you compare the mobile to the desktop chips, though. Desktop i5s are quad-core, while the mobile chips used in the Air (i5 or i7) are dual core. The 15" and 17" MacBook Pro use versions of the mobile chips that are quad core, but they are too hot to use in the MacBook Air.
 
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jmcgeejr

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Oct 7, 2010
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The chip is pretty much the same. It just runs a bit slower while performing normal tasks in order to conserve power. The 1.6GHz i5 can boost up to 2.0GHz when running both cores. The 1.7GHz model can go up to 2.4GHz, and the 1.8GHz i7 can go as fast as 2.6GHz. By contrast, the 2.4GHz i5 in the base 13" MacBook Pro can boost both cores to 2.7GHz. Thus, while the Pro runs at a higher base speed, when both are running at full throttle there isn't as much difference.

The difference gets bigger when you compare the mobile to the desktop chips, though. Desktop i5s are quad-core, while the mobile chips used in the Air (i5 or i7) are dual core. The 15" and 17" MacBook Pro use versions of the mobile chips that are quad core, but they are too hot to use in the MacBook Air.
I still wish intel offered the cpu app for osx so I could stop my cpu from throttling up and down, I would rather lock it at a slower proc speed and get better battery.
 
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gentlefury

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Jul 21, 2011
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this "watered down" term is a misnomer.

The cpu's in the Air aren't "less powerful" than their larger counterparts.

They have a built in "throttling" for both reducing heat created, and increasing battery life.

Normal state of this CPU (for example i5-2467M) is 1.6GHZ. However, when under heavy enoguh load, and I believe while plugged in, it will clock itself up to 2.3Ghz, which i believe is on par for the similarly modeled pro.

This is not "watering down" the CPU. But a power conservation method used in these ultra books

A little table of real clock speed, versus the throttled
CPU - Lowpower mode - High power mode
i5-2467M - 1.6ghz - 2.3ghz
i5-2557M - 1.7ghz - 2.7ghz
i7-2677M - 1.8ghz - 2.9ghz
^^ yes, they aren't slower...just throttled...they are faster as they need to be.
 
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jmgregory1

macrumors 68000
Also, one thing to remember is that the MBA's use of SSD drives significantly speeds up the perceived speed of the Air's compared to the non-SSD Pro's. Unless you're doing processor intensive work, you would think the Air's are faster than the Pro's processors.

I've directly compared my wife's work 13" Pro to my work 13" base Air and there is no contest - at least for docs, spreadsheets, web, email. I thought something was wrong with her new Pro because it was just so slow. She often grabs my computer to do things on because it is so much faster than her Pro.
 
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thekev

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Aug 5, 2010
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In real life, the MBA 13" base i5 processors are as fast, if not faster, than my i5 processors at work (HP). IMHO
This is another misconception :rolleyes:. First of all "i5" means nothing. It's a moniker rather than a cpu model. You don't mention generation or anything. You don't mention difference in ram. In terms of loading applications and anything off the boot drive, or dealing with any programs that hit virtual memory for any reason, the SSD makes a big difference. Basically it's impossible to generalize here unless something is physically wrong with the HP (and I am not exactly a fan of HP). Being made by Apple though does not magically make things faster, and I still end up spending time optimizing settings on a new Mac in OSX or bootcamp.

Also, one thing to remember is that the MBA's use of SSD drives significantly speeds up the perceived speed of the Air's compared to the non-SSD Pro's. Unless you're doing processor intensive work, you would think the Air's are faster than the Pro's processors.

I've directly compared my wife's work 13" Pro to my work 13" base Air and there is no contest - at least for docs, spreadsheets, web, email. I thought something was wrong with her new Pro because it was just so slow. She often grabs my computer to do things on because it is so much faster than her Pro.
Apple uses a horrendously clunky file system (HFS+). I mean it's quite possibly one of the worst things about Macs and the reason I still use disk warrior. HFS+ and spotlight combined account for a large amount of this kind of clunky behavior. If you drag all of your system data to the privacy tab via spotlight preferences and run disk warrior occasionally (if you have it) it pretty much clears up these problems assuming you have enough ram that it doesn't need to use the drive as a secondary source. If your HDD is really full, that could also make a difference. Now if you installed an SSD in your macbook pro, this perceived dysfunctionality would go away :).
 
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jdechko

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Jul 1, 2004
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I still wish intel offered the cpu app for osx so I could stop my cpu from throttling up and down, I would rather lock it at a slower proc speed and get better battery.
I'm not so sure that is necessary. Intel has a lot of speed-stepping / throttling technology in their chips to improve battery life. Also, "rush-to-idle" is a big factor when comparing chip speeds.

anandtech said:
Let’s say we have two CPUs. The first is an ultra low power CPU that only consumes 10W under load, but 0.5W at idle. The second is a high performance CPU that consumes 40W under load and 1W at idle. If it takes the first CPU 5ms to decode a frame of video at 10W but the second CPU can do it in 1ms, the total energy consumed over 33ms is is 0.064J for the first CPU and only 0.036J for the second CPU.

The longer the first CPU is idle, the more its typical and idle power advantages will come into play (hence the results in the light web browsing test). The more CPU bound the workload however, the more the advantage over the second more high performance CPU will disappear. Our heavy downloading/multitasking test is the most CPU bound of all of our battery life tests and the workload is consistent regardless of how fast you execute it. In other words, a faster CPU won’t be able to do more work, it’ll just be able to rush to idle quicker.

Link
Additionally, applications like coolbook don't increase battery life by throttling the CPU, but by limiting the voltages (power to the CPU). Coolbook doesn't work on the i-Series CPU's though, so it's not really applicable here.
 
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jdechko

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If you drag all of your system data to the privacy tab via spotlight preferences... it pretty much clears up these problems assuming you have enough ram that it doesn't need to use the drive as a secondary source.
Is there any evidence to support this, or are you basing this on personal experience alone? (Just wondering)
 
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thekev

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Is there any evidence to support this, or are you basing this on personal experience alone? (Just wondering)
I've tested it on many systems :). Getting the settings just right can help immensely on certain applications. I'm sure we can agree that the SSD only offers any benefit when the performance penalty is tied to the hard drive. The hard drives get slammed too much if the machine has to free up ram for any reason. The directory structure in the HFS+ file system usually means a lot of unnecessary seeking. OSX is kind of clunky in this regard.



I have SSD in all my Macs and the haul! My Mac Mini tho is a 2010 with a dual core and my Macbook Air BLOWS it away!
I am guessing it's a core2duo right? Core2duo was succeeded by the i3/i5/i7 cpus under the nehalem architecture and that was replaced by Sandy Bridge. If you own a Sandy Bridge macbook air, it doesn't surprise me that it blows away the mini (which was not that fast in 2010 when you purchased it). If it's a core2duo Air, then I might be surprised if you actually went into specifics rather than a generic "blows it away" comment. I can't really derive anything from that. What slows down with your mini? I have some older machines here too (core2duo era) that still open safari or word quickly. Even on my older machines, I rarely see the spinning wheel.


Edit to clarify: I don't consider the Air cpu to be watered down. I'm going to look into exactly how the parts are derived later, but my understanding is that they're simply optimized for power efficiency rather than absolute maximum speed. Performance per watt is really quite high.
 
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thundersteele

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Oct 19, 2011
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Lets compare the 13'' MBA and 13'' MBP processors.

Air: i5 - 2557M
clock speed: 1.7 GHz
max turbo boost: 2.7 GHz
L3 cache: 3 MB
bus/core ratio: 17
TDP: 17 W


Pro: i5 - 2430M
clock speed: 2.4 GHz
max turbo boost: 3.0 GHz
L3 cache: 3 MB
bus/core ratio: 24
TDP: 35 W


It's quite remarkable that the CPU in the air reaches almost the same turbo frequencies as the pro CPU, with half the power consumption.
I don't think the notion of "watered down" i5 is correct. It is a different CPU optimized for a different purpose. Just downclocking a normal i5 would not give this huge improvement in power consumption. This is also reflected by the price, which is higher for the low power CPU used in the Air.
 
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gentlefury

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Jul 21, 2011
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I've tested it on many systems :). Getting the settings just right can help immensely on certain applications. I'm sure we can agree that the SSD only offers any benefit when the performance penalty is tied to the hard drive. The hard drives get slammed too much if the machine has to free up ram for any reason. The directory structure in the HFS+ file system usually means a lot of unnecessary seeking. OSX is kind of clunky in this regard.





I am guessing it's a core2duo right? Core2duo was succeeded by the i3/i5/i7 cpus under the nehalem architecture and that was replaced by Sandy Bridge. If you own a Sandy Bridge macbook air, it doesn't surprise me that it blows away the mini (which was not that fast in 2010 when you purchased it). If it's a core2duo Air, then I might be surprised if you actually went into specifics rather than a generic "blows it away" comment. I can't really derive anything from that. What slows down with your mini? I have some older machines here too (core2duo era) that still open safari or word quickly. Even on my older machines, I rarely see the spinning wheel.


Edit to clarify: I don't consider the Air cpu to be watered down. I'm going to look into exactly how the parts are derived later, but my understanding is that they're simply optimized for power efficiency rather than absolute maximum speed. Performance per watt is really quite high.
I have a 2010 Mini and the latest 2011 Air.
 
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thekev

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I have a 2010 Mini and the latest 2011 Air.
Your 2010 mini uses a 2008 era cpu and chipset. I just looked it up. It used the P8600 and P8800 cpus so similar to a 2008 era macbook pro. They aren't bad machines, but they're totally different cpu/chipset generations. Your mini may have debuted in 2010, but the parts to make it came out in 2008, and the architecture came out closer to 2007. Apple just used core2duo way too long.

Edit: I just noticed the reason.... they used it to prolong the use of NVidia integrated gpus as opposed to having to switch to Intel (note the frequent complaints about intel's integrated graphics). The lawsuit from Intel made it impossible for NVidia to continue development.
 
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gentlefury

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Your 2010 mini uses a 2008 era cpu and chipset. I just looked it up. It used the P8600 and P8800 cpus so similar to a 2008 era macbook pro. They aren't bad machines, but they're totally different cpu/chipset generations. Your mini may have debuted in 2010, but the parts to make it came out in 2008, and the architecture came out closer to 2007. Apple just used core2duo way too long.

Edit: I just noticed the reason.... they used it to prolong the use of NVidia integrated gpus as opposed to having to switch to Intel (note the frequent complaints about intel's integrated graphics). The lawsuit from Intel made it impossible for NVidia to continue development.
yeah, like I said, its slow, but its only used as a media player, so I don't care.
 
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doktordoris

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Mar 14, 2009
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I've tested it on many systems :). Getting the settings just right can help immensely on certain applications. I'm sure we can agree that the SSD only offers any benefit when the performance penalty is tied to the hard drive. The hard drives get slammed too much if the machine has to free up ram for any reason. The directory structure in the HFS+ file system usually means a lot of unnecessary seeking. OSX is kind of clunky in this regard.





I am guessing it's a core2duo right? Core2duo was succeeded by the i3/i5/i7 cpus under the nehalem architecture and that was replaced by Sandy Bridge.
Wasn't Nehalem replaced by westmere, which itself was then replaced by Sandy?
 
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jeremyshaw

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Oct 29, 2011
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Wasn't Nehalem replaced by westmere, which itself was then replaced by Sandy?
Technically....


Nehelam -->Bloomfield/Westmere-->Sandy Bridge-E-->Ivy?

...."".....--->Lynnfield/Clarksdale-->Sandy Bridge-->Ivy?

The big honkin' LGA1366 quads were called Bloomfield. Westmere is a slightly tweaked 32nm Bloomfield design, Lynnfield was the "client" version of Nehelam, with clarksdale being the 32nm refresh of it (only to hit lower price points that were still being held by C2D arch). Nehelam was a serious mess in Intel's normal release cycle, with the "server" high end launching first (and first for a long while, too).
 
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thekev

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Aug 5, 2010
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yeah, like I said, its slow, but its only used as a media player, so I don't care.
I didn't mean to put your machine down or anything. I thought it was important to maintain proper perspective on what was being compared in that there's quite a difference in the hardware generations used between the two machines. For your present use, I'm still a little surprised that the difference is so noticeable.

Wasn't Nehalem replaced by westmere, which itself was then replaced by Sandy?
Westmere was a die shrink. I didn't really look into the full lineup there. On the Xeon end it only received a bump on the top cpu models.

Since I mentioned the 2010 mini, it did still in fact use a core2duo. Core2duo was replaced by the nehalem architecture (i3,i5,i7). The die shrink meant very little at the lower end of things. Sandy bridge hit this year, and the Mini basically skipped anything with a nehalem chip going core2duo to sandy bridge.


Technically....


Nehelam -->Bloomfield/Westmere-->Sandy Bridge-E-->Ivy?

...."".....--->Lynnfield/Clarksdale-->Sandy Bridge-->Ivy?

The big honkin' LGA1366 quads were called Bloomfield. Westmere is a slightly tweaked 32nm Bloomfield design, Lynnfield was the "client" version of Nehelam, with clarksdale being the 32nm refresh of it (only to hit lower price points that were still being held by C2D arch). Nehelam was a serious mess in Intel's normal release cycle, with the "server" high end launching first (and first for a long while, too).
You explained it better :). Intel has been all over the place the past couple years. Some parts of their line leap ahead while others stagnate. It's quite annoying. They did drop pricing on some of the Xeon parts that were on sort of extended refresh cycles, but Apple (and many of the other oems) haven't done much with machine pricing to reflect this.
 
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KPOM

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Westmere was a die shrink. I didn't really look into the full lineup there. On the Xeon end it only received a bump on the top cpu models.


You explained it better :). Intel has been all over the place the past couple years. Some parts of their line leap ahead while others stagnate. It's quite annoying. They did drop pricing on some of the Xeon parts that were on sort of extended refresh cycles, but Apple (and many of the other oems) haven't done much with machine pricing to reflect this.
It will be interesting to see how Intel markets the Ivy Bridge. They called the Sandy Bridge the "2nd generation Intel Core processor," basically ignoring Westmere, which was a die shrink only. Ivy Bridge is technically a "tick" in the tick-tock schedule, but since the IGP is improving significantly and they are introducing the tri-gate chip and variable TDP technology that will help power consumption, it will make a substantive difference. I wonder if they will call it the "3rd Generation" and then designate Haswell (a new architecture altogether) the "4th Generation" or ditch the Core i3/i5/i7 nomenclature altogether.

Anyway, by the time we get to Haswell, I don't think we will be having this discussion. Intel has promised that the mainstream chips will have the same power consumption (around 17W) that today's ULV chips get. We will likely also see quad-core processors in Ultrabooks and the Air at that point (unless Apple does something radical like introduce an ARM-powered Air).
 
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