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Sandy Bridge battery life - dual core vs quad core

post #1 of 5
Thread Starter 
I intend to buy a new laptop this year, following the lauch of the much-anticipated Sandy Bridge. I bought my last laptop, which sports a Core 2 Duo T8300 2.4 GHz processor, in 2008, and, although it still handles most tasks quite well, I could definitely benefit from a significant speed boost. However, this decision became more imminent since my laptop had its screen damaged last week. I can certainly have my screen repaired, but that there is no point in fixing it if I am going to replace the laptop anyway.

I've noticed that there are some new laptops with a quad-core Sandy Bridge processor. I've read some tests and even the i7-2630QM (which represents the low-end of these processors) seems to be faster than any Clarksfield (even the almighty i7-940XM).

In addition, this processor seems to be more power-efficient than the Arrendale. I've read reports that a Sager NP5160 sporting an i7-2630QM has a battery life of 4.5-5 hours or even 6 hours (with NVIDIA GT540M disabled). That's a lot of time, considering that the battery of previous Sager notebooks would be drained after only 2 hours of use or even less.

I understand that this increase in battery life comes, to a large extent, from the gymnics Intel has done with its integrated graphics. However, as far as I am concerned, quad-core processors still consume more power than dual-core processors. A Core i7-2630QM has a TDP of 45W; the dual-core Sandy Bridge, on the other hand, will have a TDP of 35W. I have no doubt that the dual-core Sandy Bridge would be more power-efficient than the quad-core. But I wonder how much more efficient it will be.

I am not aware of any tests or reviews of dual-core mobile Sandy Bridges nor of any report of Intel on this respect. No real facts, just thoughts posted in forums. I've read thoughts that a dual-core Sandy Bridge would allow notebooks with an 8-hour battery life. But I've also read that most of this power efficiency comes from the integrated graphics and that a dual-core Sandy Bridge would not allow a significant increase in battery life over the quad-core Sandy Bridge (it would be about half an hour). While I believe the truth is in the middle, I would like to further investigate this matter, so I can decide whether to buy a laptop with a quad-core Sandy Bridge now or wait until the dual-core is available.

Any thoughts on this issue? I would much appreciate if someone had more information (real facts) on this. Thank you in advance.
post #2 of 5
I guess we just have to wait for a 1st hand-on review of a Sandy Bridge notebook somewhere (or maybe here at NBF)

cheers ...
post #3 of 5
TDP ratings are for heat (thermal power) dispersion requirements and not directly related to energy requirements. With that said, there is an obvious correlation between TDP and energy used and a lower TDP rating will likely mean a CPU that uses less energy.

One of the factors that allowed dual-core Arrandale processors to get significantly better battery life than their quad-core Clarksdale brethren was the in-chip integrated graphics and graphics switching technologies that could only be utilized with Arrandale. This effect is minimized with Sandy Bridge processors since both variants have on-chip integrated graphics.

However, I'm inclined to believe that the dual-core variants will still have better battery life as suggested by the lower heat output. My guess would be an average of an hour difference in battery life between dual-core and quad-core. However, firm numbers won't be available until the dual-core chips come out next month.
post #4 of 5
Thread Starter 
Quote:
Originally Posted by Djembe View Post
TDP ratings are for heat (thermal power) dispersion requirements and not directly related to energy requirements. With that said, there is an obvious correlation between TDP and energy used and a lower TDP rating will likely mean a CPU that uses less energy.

One of the factors that allowed dual-core Arrandale processors to get significantly better battery life than their quad-core Clarksdale brethren was the in-chip integrated graphics and graphics switching technologies that could only be utilized with Arrandale. This effect is minimized with Sandy Bridge processors since both variants have on-chip integrated graphics.

However, I'm inclined to believe that the dual-core variants will still have better battery life as suggested by the lower heat output. My guess would be an average of an hour difference in battery life between dual-core and quad-core. However, firm numbers won't be available until the dual-core chips come out next month.
That's great, thank you!

I suspect that there are also other factors that made Arrendale's battery life superior to Clarksfield, namely the fact that it was built on 32nm process instead of 45nm. This difference also does not exist on Sandy Bridges.

An improvement of one hour in battery life wouldn't be a lot, given quad-core Sandy Bridges are reportedly getting a battery life of 5-6 hours...
post #5 of 5
One of the things Sandy Bridge is supposed to be better at is better at controlling the resources and turning things off when they are being used. If this is true if then doing certain tasks the battery life should not be much different. Now if your using software that takes advantage of the quad core that will probably use more power and result in shorter battery life between charges.
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