Memory speed tiers
Memory speed tiers The ceiling a RAM test is read against.
Each tier is a data rate, the number in a name like DDR5-6000. Its theoretical peak bandwidth is arithmetic on that number and the width of the memory bus, and every figure below shows the arithmetic.
Peak bandwidth in gigabytes per second is the data rate in megatransfers per second, times the bus width in bits, divided by 8 bits per byte and by 1,000. It is a ceiling: no real workload reaches it, and the RAM speed test measures what the memory actually delivers, which always lands below it.
DDR4
A DDR4 module has a 64-bit data bus. Two modules in dual channel make a 128-bit bus.
| Tier | Data rate | Peak at 64-bit | Peak at 128-bit |
|---|---|---|---|
| DDR4-3200 | 3,200 MT/s | 25.6 GB/s | 51.2 GB/s |
DDR5
A DDR5 module also carries 64 data bits, split into two independent 32-bit subchannels. Two modules in dual channel make a 128-bit bus.
LPDDR5X
LPDDR5X is soldered beside the processor in 16-bit channels, and the processor sets how many there are. The total width is a property of the laptop's processor, not of the memory.
| Tier | Data rate | Peak at 64-bit | Peak at 128-bit |
|---|---|---|---|
| LPDDR5X-7500 | 7,500 MT/s | 60 GB/s | 120 GB/s |
| LPDDR5X-8533 | 8,533 MT/s | 68.264 GB/s | 136.528 GB/s |
| LPDDR5X-9600 | 9,600 MT/s | 76.8 GB/s | 153.6 GB/s |