Memory systems and methods for improved power management

A method for reading data from a rank of memory devices, the rank of memory devices including a first sub-rank of memory devices on a first memory module and a second rank of memory devices on a second memory module, the method comprising:

• receiving a rank read command at the first memory module;
• relaying a delayed version of the rank read command to the second memory module, the delayed version of the rank read command delayed relative to the rank read command by a read-command delay;
• issuing a first sub-rank read command responsive to the rank read command to the first sub-rank of memory devices on the first memory module;
• issuing a second sub-rank read command time aligned with the first sub-rank read command responsive to the delayed version of the rank read command to the second sub-rank of memory devices on the second memory module;
• and
• conveying a first portion of the read data from the first sub-rank of memory devices on the first memory module responsive to the first sub-rank read command and a second portion of the read data from the second sub-rank of memory devices on the second memory module responsive to the second sub-rank read command.