Why RAM speed is counted in transfers
DDR stands for double data rate. The memory sends data on both the rising and the falling edge of its clock, so it makes two transfers per cycle. A DDR5-6000 module has a 3000 MHz clock and makes 6000 million transfers a second. MT/s counts those transfers, which is why it's the honest unit.
Boxes and spec sheets often write 6000 MHz anyway. That's the transfer rate under a looser label, and some tools show the real 3000 MHz clock instead. If you see two numbers for one kit and they're a factor of two apart, this is why.
From MT/s to GB/s
A standard memory channel is 64 bits wide, so each transfer moves 8 bytes. Peak bandwidth is the data rate × 8 bytes. DDR5-6000 peaks at 48.0 GB/s per channel, and 96.0 GB/s with two channels. A DDR5 module is split into two 32 bit subchannels, but together they still add up to 64 bits.
- DDR4-3200: 25.6 GB/s
- DDR5-4800: 38.4 GB/s
- DDR5-6000: 48.0 GB/s
- DDR5-8000: 64.0 GB/s
DDR5-6000 peaks at 1.9 times the bandwidth of DDR4-3200. Those are ceilings. Real programs reach a share of them.
A higher rate doesn't mean lower latency
Each step up in MT/s shortens the clock cycle: 0.417 ns at DDR5-4800, 0.333 ns at DDR5-6000 and 0.250 ns at DDR5-8000. Timings count cycles, though, so what matters is how many cycles a kit needs. DDR5-4800 CL40 waits 16.7 ns, DDR5-6000 CL30 waits 10.0 ns and DDR5-8000 CL38 waits 9.5 ns.
Going from 6000 to 8000 MT/s adds 33% to the data rate, but the wait falls only 5%. MT/s tells you about bandwidth. Latency needs the timings too.
What the label usually means
JEDEC's standard DDR4 rates stop at 3200 MT/s, and DDR5 starts at 4800 MT/s. A kit sold faster than those relies on an XMP or EXPO profile, and the BIOS has to apply it. Until it does, the module runs at a JEDEC speed.
Your CPU and motherboard set how fast memory can run, so check the board's memory support before paying for a faster kit. The DDR5-6000 CL30 vs DDR5-8000 CL38 comparison shows what the extra speed buys.