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Door staff@engadget.com (Luke James) - 04 Oct 2026
All DDR5 kits are labeled with a four-digit number, like DDR5-6000 CL30. The number appended to DDR5-XXXX is the data rate in millions of transfers per second, while CLXX is the latency, counted in clock cycles. Many people confuse the data rate with clock speed because it looks like a clock speed. But it isn't. The clock in a DDR5-6000 kit ticks at 3,000 MHz, and the memory moves data on both the up and down stroke, hence 6000.
CL30 or CL36 is the CAS latency. In other words, it's the clock cycles between the processor asking for something and the memory responding. And because those cycles get shorter as the clock climbs, a DDR5 kit can have a bigger CL and still be no slower to respond. Multiply the CL by 2000, divide by the data rate and you'll have the real figure in nanoseconds: 10 for a DDR5-6000 CL30 kit and nearly 17 for a "bargain" DDR5-4800 CL40 one.
JEDEC's standard timings keep that number close to 14 nanoseconds all the way from DDR5-3200 to DDR5-8800, so a faster kit with proportionally looser timings isn't quicker off the mark, just wider once data's flowing. Such is the difference between budget kits, which sit at DDR5-6000 with CL36 or CL40, and premium ones, which either tighten to CL30 or CL28 at the same speed or push on to DDR5-9600 with CL34 to CL46.
CL30 or CL36 is the CAS latency. In other words, it's the clock cycles between the processor asking for something and the memory responding. And because those cycles get shorter as the clock climbs, a DDR5 kit can have a bigger CL and still be no slower to respond. Multiply the CL by 2000, divide by the data rate and you'll have the real figure in nanoseconds: 10 for a DDR5-6000 CL30 kit and nearly 17 for a "bargain" DDR5-4800 CL40 one.
JEDEC's standard timings keep that number close to 14 nanoseconds all the way from DDR5-3200 to DDR5-8800, so a faster kit with proportionally looser timings isn't quicker off the mark, just wider once data's flowing. Such is the difference between budget kits, which sit at DDR5-6000 with CL36 or CL40, and premium ones, which either tighten to CL30 or CL28 at the same speed or push on to DDR5-9600 with CL34 to CL46.