Bandwidth considerations (see Jef Poskanzer http://www.acme.com/build_a_pc/bandwidth.html)
Pentium 4 FSB 64bits 100MHz QDR 3.2 GB/s 25.6 Gbps
Interface Width Frequency Bytes/Sec Bits/Sec
2-channel PC800 RDRAM 2x16bits 400MHz DDR 3.2 GB/s 25.6 Gbps
PC2100 SDRAM 64bits 133MHz DDR 2.1 GB/s 17 Gbps
EV6 bus (Athlon/Duron FSB) 64bits 100MHz DDR 1.6 GB/s 12.8 Gbps
PC1600 SDRAM 64bits 100MHz DDR 1.6 GB/s 12.8 Gbps
PC800 RDRAM 16bits 400MHz DDR 1.6 GB/s 12.8 Gbps
PC150 SDRAM 64bits 150MHz 1.3 GB/s 10.2 Gbps
133MHz FSB 64bits 133MHz 1.06 GB/s 8.5 Gbps
AGP 4x 32bits 266MHz 1.06 GB/s 8.5 Gbps
100MHz FSB 64bits 100MHz 800 MB/s 6.4 Gbps
PC100 SDRAM 64bits 100MHz 800 MB/s 6.4 Gbps