R520, Radeon X1800 has 512 bit internal memory controller

ATI managed to make some kind of internal 512 bit controller that will enable them to use 512 bit memory. This memory is available at Samsung and ATI prototype showed here is using those 1600 MHz 512 Mbit chips. You can find some additional details about this memory here.

Geforce 7800 GTX and all Nvidia 6800 generation cards are using 256 bit memory and 256 bit memory controller so this kind of comes as a surprise to us. ATI won't be able to take the full advantage of 512 bit memory and that the memory will operate as a 256 memory but will save some cost to ATI.

We don't know all the details but we believe that 512 bit memory controller can help you to use less chips on your board. I believe that you don't have enough interconnections on the PCB to take the full advantage of 512 bit memory controller.

As top range Radeon X1800XT is going to be launched as 600 / 1400 MHz card we believe that there will be much overclocking headroom as this memory is actually specified to work at 1600 MHz. it still won't save ATI for having limited availability of those super high end parts. µ