Also known as “DDR-400.” A rating for the performance of DDR SDRAM chips. The “3200” portion represents the transfer rate in MBps (megabytes per second), so with PC3200 RAM, the chips are rated for 3.2GBps (gigabyte per second) speeds. PC3200 chips are DDR chips, so they have a clock speed of 200MHz resulting in 400 million transfers per second.
The PC rating for a DDR SDRAM chip is calculated using the formula:
clock rate x 2 (for DDR) x 64 (bits per transfer) / 8 (bits per byte)