In the ideal case synchronous means that the internal pulsing of the processor is as high as the pulsing of the RAM memory module. For the former chip sets the asynchronous variant had been used more frequently than the synchronous one. A Duron processor with a pulse frequency of 1300 MHz an FSB pulse frequency of 100 MHz and a DDR333 memory module with a pulse frequency of 166 MHz can not be synchronized to a pulse frequency of 100 MHz. Here it is better to leave the memory module with a pulse frequency of 166 MHz. Nowadays this problem is solved by the Dual Channel which allows the synchronization.
