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slnko-v-sieti
Nov 30, 2011, 12:47 PM
This recent news piece (http://www.computerworld.com/s/article/9222196/Larger_15_in._MacBook_Air_makes_sense_for_Apple_say_analysts) from ComputerWorld reiterates ("will double battery life[...]") some claims (http://www.computerworld.com/s/article/9220101/Intel_boosts_laptop_battery_graphics_with_Ivy_Bridge) Intel made about the battery improvements Ivy Bridge will bring to the MBA:

CPU and graphics processor will be integrated on a single chip, and deliver double the performance-per-watt compared to Core processors based on the Sandy Bridge microarchitecture[...] users will also see significant power and performance enhancements with Ivy Bridge, which will consume up to half the power at the same performance as current Sandy Bridge chips, said Intel's senior fellow Tom Piazza. Piazza said Ivy Bridge could alternately deliver double the performance on the same power consumption as Sandy Bridge chips, depending on how the chip is used.

For being an incremental update, doesn't doubled battery life (best case scenario) seem like a huge jump?



thekev
Nov 30, 2011, 01:01 PM
They play with their numbers quite a lot. I think double would require more than just cpu/gpu changes. Displays and drives consume a fair amount of power. I'm not sure what the power budget on the Air's SSD is though.

Ivy Bridge is supposed to essentially throttle down when the machine isn't being full utilized. If you're fully taxing the machine, you're unlikely to see a really significant increase in battery life.

Xikum
Nov 30, 2011, 03:07 PM
I read that although they are reducing the power-consumption of the CPUs, they are going to make them more powerful and have more cores; therefore, the extra power that is saved is used to power the 4 individual cores. So there isnt a net increase or decease in actual battery life of the laptop, but instead you get a performance increase without sacrificing battery life.

Could be 100% incorrect though.

waloshin
Nov 30, 2011, 03:41 PM
Impossible.
Besides what are we going to have a 700 - 900 mhz Macbook Air?

pgiguere1
Nov 30, 2011, 05:23 PM
Impossible.
Besides what are we going to have a 700 - 900 mhz Macbook Air?

This. They talk about double performance per watt. That would mean that they would need to make the chip as fast as a Sandy Bridge to have double the battery life. That would mean underclocking to about half its original frequency.

I bet they won't underclock it, it'll just be faster. But if you wish, underclock it yourself if you like laptops that run cool and last long. I think 2x is a bit too optimistic though.

jdechko
Nov 30, 2011, 06:51 PM
Two things about this thread.

1) The original quote doesn't say "double battery life". It talks about double performance, and power savings up to 50%. But it doesn't say IB will double the battery life.

2) CPU performance is only one variable when calculating battery life. Screen brighness and radio antennas (WiFi, Bluetooth & 3G) are also significant contributors. Even the RAM and SSD take up some juice.

Not to say that we won't see improved battery life, but I expect maybe an additional hour or two at most.

amarcus
Nov 30, 2011, 07:14 PM
Some good applicable advice to live by: Set your expectations low and you'll always be impressed!

I wouldn't expect more than an hour of extra battery life with Ivy bridge...

Scottsdale
Dec 1, 2011, 01:09 AM
It isn't just the CPU that uses the battery though... so it doesn't equate to the MBA's battery lasting twice as long. Running the display has to require a massive amount of the battery itself.

thejadedmonkey
Dec 1, 2011, 01:18 AM
It isn't just the CPU that uses the battery though... so it doesn't equate to the MBA's battery lasting twice as long. Running the display has to require a massive amount of the battery itself.

Assuming the CPU can clock down to the current speeds of the current CPU's (which would mean it would use 1/2 the power as current CPU's), and assuming that a CPU uses ~30% of a laptop's power (I heard that years ago), you'd be saving 15% of a laptop's power, or giving the laptop 15% extra runtime... shared with all of the components. So lets say an extra hour, tops. That's not much different from any other previous gen to current gen improvements.

I hope I'm wrong, but somehow my armchare mathmatics feels right.

eljanitor
Dec 1, 2011, 01:24 AM
I've also heard claims that the ivy bridge processor reduces power consumption. I haven't heard that it cuts power consumption in half until reading this.

Also if Apple decides to drop Intel and go with ARM processors in its entire line of products, we may never see the ivy bridge in action in a Mac since it's not supposed to be for sale to the public until Spring of 2012.

http://www.tomshardware.com/news/ivy-bridge-processor-release-22nm-3d-transistor,13753.html

halledise
Dec 1, 2011, 04:14 AM
They play with their numbers quite a lot.

and some other things too ;)

Roman2K~
Dec 1, 2011, 04:39 AM
Also if Apple decides to drop Intel and go with ARM processors in its entire line of products, we may never see the ivy bridge in action in a Mac since it's not supposed to be for sale to the public until Spring of 2012.
Maybe ARM is the reason why Q1 release dates are rumored despite Ivy Bridge being supposed to arrive early Q2.

That may also be what the switch back to nVidia is all about... They're making quad-core ARM SoCs these days (starting with Tegra 3 (http://en.wikipedia.org/wiki/Tegra#Tegra_3_.28Kal-El.29_series)).

But raw CPU performance would be way below that of Intel's x86 processors. I don't really care about performance so I wouldn't mind given the benefits (battery life, heat).

There's an interesting discussion about the improbability of Apple switching to the ARM architecture in this article (http://www.realworldtech.com/page.cfm?ArticleID=RWT050911220752&p=2).

slnko-v-sieti
Dec 1, 2011, 09:11 AM
1) The original quote doesn't say "double battery life". It talks about double performance, and power savings up to 50%. But it doesn't say IB will double the battery life.
Yeah, that's why I went back to the original, to see if it was really the same claim. It's easy to see where they made the leap in logic.

Thanks for the insights, all. I was really surprised to see that claim not being propagated across news websites, and now it's clear why.

Aras87
Dec 1, 2011, 07:27 PM
Impossible. I will be impressed if ivy bridge can add another 30-45mins to the total runtime. In casual use, thanks to Sandy bridge, cpu does not use a lot of power anyway. They have to do something about the screen and the wireless stuff if they really want to improve the battery life drastically.