In a posting over at Gizmodo, Matt Buchanan reports that, according to NVIDIA, the two graphics chips used in the new MacBook Pros, the integrated 9400M and dedicated 9600M GT, are quite capable of running together in an SLI setup, a feature that the MacBook Pros do not offer.
Furthermore, NVIDIA claims that the limitation of having to log out and back in to switch between the two GPUs exists only on the software level and, by default, the graphics cards are capable of allowing the user to switch between them on the fly. Also, these new chips can theoretically support up to 8GB of RAM.
If true, and we have no reason to doubt their authenticity, these are quite interesting tidbits of information that hint, yet again, at the possibility that Apple has put in place artificial limitations via software on which features of the hardware can be utilized.
Although I can see the rationale behind not allowing simultaneous use of the two graphics processors, given how battery intensive each one of them individually is, I fail to see why Apple wouldn’t figure out a way to allow users to switch between the two GPUs on the fly, perhaps even automatically based on when the notebook is on battery power and when it is plugged in.
I imagine that it must be quite a hassle to have to stop everything you’re doing and log out if you ever want to switch between them. In all likelihood, given the fact that I only ever reboot my Mac when software updates require me to, I would never even utilize the second card due to this cumbersome requirement. Therefore, it is surprising that Apple, especially Apple, didn’t make the process easier even though it was technically possible.
Also, if the GPUs support up to 8GB of RAM, why is the maximum capacity of the Mac notebooks still stuck at 4GB? I was hoping it would be bumped up to at least 6GB. MacBook Pro buyers, in particular, can use all the speed and performance they can get.
Since all the required hardware is already in place, maybe Apple will eventually bless us with a software update that will enable some or all of these features, huh? What say you, dear readers?
I doubt that Apple has artificially limited the capability of the chipset. Something that is "technically possible" is not necessarily easy. The new MacBook Pro shipped with the current version of the OS (albeit a newer build). To support the new hardware capability, the OS will have to accommodate it at a low level. In time, I expect that on-the-fly graphics processor switching and dual-graphics processor mode will be enabled (maybe with Snow Leopard?).
And while the chipset supports 8 GB of memory, with two slots that means 4 GB RAM modules would be necessary. Until such chips are commonly available, Apple will not offer that option.
Lying is part of the business.
I suspect there's a limitation somewhere under the hood stopping the instant switching between the two, and that 10.6 will fix it.
As for the RAM thing, can you actually buy 4GB DDR3 sticks suitable for the MBP right now?
Steve jobs will eventually allow switch on the fly and simultaneous running of both graphic chips if you shell out $100+ for Mac OS 10.6 or equivalent software update.
I'll chime in and guess that live switching requires some changes under the hood that're not ready. And will probably be easier to implement without having to think about PPC architecture. So Snow Leopard.
As for running both chips at the same time, while that wouldn't be a power problem for a system that is plugged in there may be thermal issues. It would be a pity to cook a new MBP.
Remember when Apple didn't use off the shelf components? Back when all the video was on the motherboard like the sound still is. We would have never heard about a feature like this if it were built in. Isn't it awesome how far we've come in a decade?
It may be easy to assume using both GPUs may sound like it may offer performance advantages. However the fact is hybrid SLI reduces the speed of the faster GPU to the speed of the slower one.
So would two Geforce 9400M's be faster than one 9600? I'm not so sure about that.
The commonly-accepted reason for the limitation is that the WindowServer has to be restarted to take advantage of the other GPU, and restarting the WindowServer is pretty much exactly the same thing as logging out. We can only hope that Snow Leopard will see a rewrite of the WindowServer to allow it to switch on-the-fly.