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You probably can, but it would be reduced to 400 MHz since that is the speed of the RAM bus.  The system bus on the Dual 2 GHz is faster than the RAM bus, but faster RAM won't help anything.

You probably can, but it would be reduced to 400 MHz since that is the speed of the RAM bus.  The system bus on the Dual 2 GHz is faster than the RAM bus, but faster RAM won't help anything.

I was hoping that the bus wasn't locked at that rated speed.  I was hoping that they used that as a base being that faster ram was very expensive and harder to get and was also not out at the time of release and or developement. 

Anyone know of a way to Overclock the Ram bus to the system controller?  Maybe that would help..

anyone with a G5 want to check out if it's locked or not?

How would one do that?

Or you could just look at the specs of the computer and find out that the speed of the memory bus is constant...

Yeah, you can't just have the RAM bus setting itself to arbitrary speeds.  That would be a lot of extra engineering (think: cost) since the bus jumpers would need to be controlled by some type of software, or hardware mechanism.  Add to that the fact that you need to test the system with all these different settings for each of the speeds and multipliers.  (Who says the motherboard would even be compatible with a variable RAM bus?)

Also, planning a motherboard on future technology isn't ever a safe bet.  Specifications change, so all that work designing a board that will work with some faster, future RAM chip might all be wasted.

It doesn't work.  It won't work.

Some busses work that way.  If you use DDR266 memory on a system that supports up to DDR 333 Mhz, it runs at the slower ram speed.  And the same in reverse up to what the Max speed of the board is.  Not to say that this works in a G5 situation.  It could be locked at a rated speed.  I was hoping that the Max on a dual 2 Ghz would be DDR 500 Mhz rated ram.  Dual channel gives you that 1 Ghz memory bandwidth, which more matches the FSB of that system.  Being that DDR 400 was most likely the fastest ram at their time of testing and building their G5 system.  It was made to work with it rather then wait for tested DDR 500 to be available and cheap enough to not bring the price of the towers up to high.