Processor, Graphics Card, and Battery Life?

I'm looking for a new notebook and just had a few questions about processors and graphics cards and how they affect battery life.

What kind of impact will new Centrino 2 processors have on battery life compared to the current Core 2 Duo processors?

And how will graphics cards impact battery life? Say, Intel Graphics Media Accelerator X3100, ATI Mobility Radeon HD 3470 with 256MB DDR2 discrete memory, and ATI Mobility Radeon HD 3650 with 512MB DDR2 discrete memory. I know using a discrete card will decrease battery life compared to integrated graphics, but will using a 3650 use more battery than a 3470? And how significant is the performance difference between these cards?

Thanks in advance.

 

Centrino is a platform, not a CPU (though it uses the new Penryn refresh of C2D series of CPUs).

Graphics cards will make a difference in battery, the question being 'how much?'. I'd say a difference of about 1/2 hr to 3/4 hr more battery life with an integrated GPU. As for those two GPUs, the power draw will likely be almost identical, though what matters is the voltage that those two draw under idle and load (which I assume ATI has set the same for each card). For performance, I'd go with the 3650 and not worry about battery life.

 

I meant the "p" processors compared to the "t" ones.

 

Oh, well at max load the P series will draw 10W less so more battery life if your processor is always maxed. At idle expect the P series to also be slightly more efficient (maybe 5-10%).

 

Not necessarily so. The vast majority of Core / Core 2 CPUs are set to run at below the maximum voltage allowed in Intel's specification. Undervolting will reduce that further. (For example, my T7300 came set to 1.25V at maximum speed but has been running at 1.1V, which saves about 10W on the peak power consumption). It is quite possible that the lower TDPs in the latest CPUs reflect Intel's confidence that they can get good yields with a lower specified maximum voltage range and not a reduction in the real life average power consumption.

John

 

True, but the average consumer doesn't know about undervolting so for them it is a reduction in power consumption.