If you have a multi-rank DDR3 UniPHY controller generated in the Quartus® II software version 12.1SP1 or later, you may see the ODT signals for multiple ranks assert simultaneously.
There is a problem with ODT when the Memory format in the Memory Parameters tab of the MegaWizard™ Plug-In Manager is set to Discrete Device.
The workaround is to change the Memory Format in the Memory Parameters tab to UDIMM.
This problem is fixed starting with the Quartus® II software version 15.0.