I just received your CSE-813MTQ-520CB chassis, being a K0 revision which was told to be 100% compatible with your X8DTxx boards but there is only one 8 pin and a 4 pin, not the 2 pieces 8 pin , which is required by the X8DTL-iF mainboard?
For CSE-813MTQ-520CB rev K0 chassis, it still comes with one 8 pin and a 4 pin. Rev K3 will have two 8 pins connector.
But when using this X8DTL-iF and system power budget less than or equal to 650W, existing power supply version is okay, just make sure to connect both 12V/8pin and 12V/4pin on the 2x8Pin MB