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 at the same time. 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.
Device Family: Stratix® III, Stratix® IV GT, Stratix® IV GX, Stratix® V E, Stratix® V GS, Stratix® V GT, Stratix® V GX
Area: EMIF, Intellectual Property
IP Product: DDR3 SDRAM Controller MegaCore supporting UniPHY
The workaround is to change the Memory Format in the Memory Parameters tab to UDIMM. This problem will be fixed in a future release of the Quartus II software.