DRAM

Which is closest to the peak bandwidth of one channel of DDR4 memory with a data rate of 3,200 MT/s and a 64-bit data bus?

  1. AAbout 204.8 GB/s
  2. BAbout 25.6 GB/s
  3. CAbout 3.2 GB/s
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Answer: B. About 25.6 GB/s

Peak bandwidth is the transfer rate times the bus width. 3,200 × 10⁶ transfers/s × 64 bits = 3,200 × 10⁶ × 8 bytes = 25.6 × 10⁹ bytes/s, or about 25.6 GB/s.

  • A. About 204.8 GB/s results from mixing up bits and bytes.
  • B. Correct. 3,200 MT/s × 8 bytes = 25.6 GB/s.
  • C. About 3.2 GB/s would correspond to an 8-bit (1-byte) bus.
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