Originally posted by boots
G4 @ 1.33 GHz, 64-bit-wide bidirectional 167MHz FSB:
-> 1.3GB/s or so max reading- or writing-bandwidth
hypothetical G5 @ 1.5GHz, 750MHz FSB (32-bit read, 32-bit write)
-> 3GB/s max reading-bandwidth
-> 3GB/s max writing-bandwidth
-> can do both at the same time.
Shoot, cut it in half one more time and go all the way down to a 375MHz FSB on the G5 (hypothetical bus divisor feature, easy to do), and one of the two 32-bit pipes on the 970 would still be faster than the 167MHz G4 MaxBus.
It'd have to be a slower bus because I can't see a laptop having a 750MHZ FSB for heat issues. We also aren't even getting into the differences between a bidirectional and unidirectional bus. I know several engineers who say the 32bit buses are a big problem for the 970 - or at least they see it as one in the future.
While there may be more bandwidth, that doesn't necessarily mean it is used. Also, as has been discussed elsewhere, the MaxBus is actually very efficient at doing what it does.
Even though the bandwidth would be greater, most numbers I've seen run still say that G4 would be pretty equal to the 970 at 1.5GHZ. Plus, the system controller makes the power drain far greater.
Besides, it may all be moot. If the e600 is delivered the FSB would likely be eliminated and the PowerBooks could have a dual core chip with direct access to the RAM. If this is in the offing, why would Apple move to the G5 in the PowerBooks? One, I say they can't do it because the required controller's requirements are too high.