Why 'better battery life' option when on mains power?

[ss957916]

In energy prefs on my MBP there's something about graphics at the top where you can select better performance or better battery life. But surely, when on mains power, surely it doesn't use battery?

 

[w00t951]

The one on the top, Better Battery life, is the integrated NVIDIA 9400M card. The Higher Performance is the discreet NVIDIA 9600GT card. The reason most people run with the integrated is a better set of drivers, and the fact that the computer does not heat up nearly as much. However, if you boot your computer with the intention to run some Photoshop or something graphically demanding, the discreet is the way to go. And during normal operation, the computer does not draw battery power. However, when there is an excessive amount of graphical and general processing going on (QED a game like Crysis or COD5) the power supply (both the 60 and 85 watt) cannot supply all of the power needed, and therefore draws some power from the battery. If you unplug the battery, the CPU will throttle down to 2.10 GHz, and the GPU will most likely switch to the integrated. If the power consumption exceeds the power supply capacity, then the computer fail epically. Don't override these settings with Terminal or something, okay?

 

[Eraserhead]

Photoshop doesn't use the graphics card really. If you are using 3D programs or Motion in Final Cut then you'll want the discrete card.

 

[ss957916]

So is the other card never used unless I select it?

 

[w00t951]

Basically. And yes, the GPU temp in my MBP skyrockets when I am in Photoshop.

 

[ss957916]

Oh - that was a waste of money then!

 

[niuniu]

Oh - that was a waste of money then!

Not for me! I'd have the 9600GT on a lot