Yes, but the primary reason is unituitive. It comes from the fact that the 360 shares the memory bank with the video card. To explain I need to go into some background though (sorry if you already know this).

It is vastly more efficient (though technically not required for the cell) for the programmer/compiler to explicitly manage (some aspects) of DMA calls on an SPU because it is composed of two different core-like things with a "division of labor" which execute in parallel. The SPE gets to slosh around in it's 256KB playground while the MFC either very quickly borrows/shares from/with the other SPEs (all the SPEs can read each other's LS with almost no overhead) or grabs things from main memory via it's DMAC. The address space of the LS accessed via real physical addresses and hence, no translations of virtual addresses (there are actually 2 levels of address virtualization on the 360!) are required and so you don't need to cache those translations with a TLB for anything the SPE does.

On a cache coherent system the equivalent of these DMAC calls would happen when a normal load by a core (call it core A) has a cache miss. Since there was a cache miss, that cache has to go out to find the data from a higher level. But what happens if another core (call it core B) already has that address in it's L1 cache (which is always written through to L2 on the 360) and has been messing with it?

You need a way to keep B informed of any changed -- usually by B's cache snooping (intercepting) all reads to that physical address in main memory and L2 cache and broadcasting to A's cache (and every other core's cache) to backoff while it updates the changes. The process of setting this up is a bit involved and while this is being set up noone can access main memory to avoid two caches simulatneously requesting and thinking they are owners of a line.

So what does this have to do with the video card?

Well, on the 360 the video card has the ability read and write directly to main memory and L2 cache! So the 360 has to maintain coherency between all the L1 caches, the L2 cache, main memory, and the caches on the video card itself via the FSB. The video cards tendency to clober mass quatities of data doesn't help either.

Well I must be in MikeB's world (who is that anyway?) becuase the Cell will still have it beat on physics despite its limitations. If the physics are good then the animation possible on the system will be better. Don't see that happen with a six core whatever (unless someone is implying the Cell is going to be in the nextbox.) You can have as detailed models graphically as you want, but realistically if your high polygon models with shader whatever support don't move in a lifelike manner then your graphics are crap. If M$ really is releasing a new console then they would do well to make sure their new CPU can handle better physics rather than higher res textures and lighthing.

M$ is a little scared if they are releasing a new console this soon, but based on the specs I would compare it to the Sega 32X. It most likely won't do as well, but of course I think the specs listed are fake.

Well I must be in MikeB's world (who is that anyway?) becuase the Cell will still have it beat on physics despite its limitations. If the physics are good then the animation possible on the system will be better. Don't see that happen with a six core whatever (unless someone is implying the Cell is going to be in the nextbox.) You can have as detailed models graphically as you want, but realistically if your high polygon models with shader whatever support don't move in a lifelike manner then your graphics are crap. If M$ really is releasing a new console then they would do well to make sure their new CPU can handle better physics rather than higher res textures and lighthing.

M$ is a little scared if they are releasing a new console this soon, but based on the specs I would compare it to the Sega 32X. It most likely won't do as well, but of course I think the specs listed are fake.

Most games use the GPU to its max but not the CPU. That's why 360 and PS3 games look quite similar, their GPUs are almost equally powered. That's also why the best upgrade you can do to a gaming PC is upgrading its GPU, upgrading the CPU will yield almost no benefit for most games.

Modern CPUs including the Cell, the Xenon and Intel CPUs have more than enough power to calculate the physics of as many objects as a GPU can handle.

What's more, a fast GPU can also be used to accelerate physics processing without hogging the GPU too much. Ever heard of PhysX?

Having said all that... do you have any practical example of a game with "crap physics" due to an underpowered CPU when the GPU is quite powerful?

@Squilliam: Yeah, that's because it's easier (and more acceptable) to scale graphics than things like AI and physics.

Everyone can understand that a game gets better resolution with a better GPU, but if the AI and physics are made scaled by CPU power, people won't like it (imagine if the enemies acted smarter on your friend's super-computer).

Scaling things like AI and physics would also make it harder to test a game... how to make sure the AI won't get too smart, or that weird physics bugs won't happen with differently-powered computers?

Most games use the GPU to its max but not the CPU. That's why 360 and PS3 games look quite similar, their GPUs are almost equally powered. That's also why the best upgrade you can do to a gaming PC is upgrading its GPU, upgrading the CPU will yield almost no benefit for most games.

Modern CPUs including the Cell, the Xenon and Intel CPUs have more than enough power to calculate the physics of as many objects as a GPU can handle.

What's more, a fast GPU can also be used to accelerate physics processing without hogging the GPU too much. Ever heard of PhysX?

Having said all that... do you have any practical example of a game with "crap physics" due to an underpowered CPU when the GPU is quite powerful?