How Fast Is Random Access Memory? RAM Speed Explained
RAM speed is measured in MT/s (megatransfers per second) for data rate and in nanoseconds for latency. Current DDR5 runs from 4,800 to 8,800 MT/s at JEDEC standard speeds, and DDR5-6000 delivers about 48GB/s of bandwidth per 64-bit channel. A typical access takes around 10 to 15 nanoseconds, which is thousands of times faster than a typical SSD.
How RAM Speed Is Measured
- Data rate (MT/s): how many transfers happen each second. DDR5-6000 means 6,000 MT/s. It is often written as MHz, but the clock is half that number because of double data rate.
- Bandwidth (GB/s): MT/s x 8 bytes per 64-bit channel. DDR5-6000 gives 6,000 x 8 = 48,000 MB/s, or 48GB/s per channel.
- Latency (CL and nanoseconds): CAS latency counts clock cycles. DDR5-6000 CL30 works out to 10 nanoseconds.
RAM Speed by Generation
| Generation | Typical speed range (MT/s) |
|---|---|
| DDR4 | 1,600 to 3,200 (JEDEC), higher with overclocking |
| DDR5 | 4,800 to 8,800 (JEDEC), higher with XMP or EXPO |
| DDR6 (expected) | 8,800 to 17,600 |
RAM vs Other Storage
RAM is the fastest main memory in a computer outside the CPU's own cache. An NVMe SSD responds in tens of microseconds, while RAM responds in tens of nanoseconds. That gap is why programs run from RAM and why running out of it, which pushes data to the drive, slows a computer down.
Frequently Asked Questions
Does faster RAM improve performance?
Yes in some tasks, such as integrated graphics, compression and some games. The gain is usually modest compared with a better CPU or GPU.
What is a good RAM speed?
DDR5-5600 to DDR5-6400 is a common sweet spot for desktops.