According X9DRW-iF manual we have to connect 4x power connectors (24, 4 and 2x 8-pins). We are using recommended chassis (815TQ-R700WB) for that board. But the chassis has only 24 and 2x 8-pins connectors. Please confirm that we are OK to use only 3x power connectors.
The 4-pin is just an option which is not required in an 1U configuration. It is used only when you have very heavy loading.