Most chipsets for the Athlon run at 133MHz DDR, or 266MHz. All chipsets for the Pentium 4 run at 100 MHz QDR, or 400 MHz, though 133 MHz QDR (533 MHz), will be available shortly. What kind of memory that is accepted is determined by the memory controller in the north bridge, not the front side bus speed. However, to determine total usable memory bandwidth, simply multiply the front side bus speed (including the pump) by the bus width (64 bits for both), then divide by 8, and you have your bandwidth in MB.
Discussion Zen 5 Speculation (EPYC Turin and Strix Point/Granite Ridge - Ryzen 9000)
Discussion Intel current and future Lakes & Rapids thread
