The parameter “CAS# Latency” (CAS# Latency Clocks) describes a very important feature of memory module – a minimal number of cycles from the moment of data request by CAS to their occurrence and stable reading from the outputs of memory module. This parameter may have 2 values: 2T and 3T (or 2 Clks and 3 Clks). The higher value is always set by default for this parameter. Decreasing the value allows speeding up the process of data reading from memory and, accordingly, increasing the system performance: setting two-tact value speeds the system up to 1-2% compared with three tacts. But not all memory micro chips will operate steadily after changing the value of this parameter. So if you buy the memory module, pay attention not only to memory specification (PC100 or PC133) but to the time of delay CAS Latency (CL). The memory with CL = 2 has maximum performance and operates steadily on frequencies of 100 – 133 MHz.
The parameter “Row Precharge Time” (SDRAM RAS Precharge Time) enables to specify the number of clocks before the cycle of memory regeneration. This parameter has got two values: 2T and 3T (or Fast and Slow). The lower value (Fast) allows increasing the performance of memory while the higher value (Slow) increases the stable operation of your computer.
The parameter “RAS# Pulse Width” specifies the number of clocks during which the signal RAS is active. This parameter may have various values: from 3 clocks (3T) to 7 (7T). Decreasing the time of RAS activity increases the system performance but some memory modules may have failures.