Via Macintouch. These notes have far more detail on the new G5s than Apple's marketing materials. The SuperDrive supports DVD+R double layer format, for example. Power supply is 180W.
Note the memory specs:
Additional DIMMs can be installed. The combined memory of all of the DIMMs installed is configured as a contiguous array of memory. The throughput of the 400 MHz memory bus is dependent on the DIMMs installed. If only one DIMM is installed, the memory bus is 64-bit. If two non-identical DIMMs are installed, there are two 64–bit memory buses. If two identical DIMMs are installed, the memory bus is 128-bit. Identical DIMM pairs have the same size and composition and provide the fastest and most efficient throughput.On PCs at least paired DIMMS have to be purchased together. So when you buy a G5 with 512MB of DRAM, you've got to sell that somehow to get the fastest memory -- or donate it to a friend!