Dear Customer,
You need to use the extra fittings and tubes to connect your GPU water block to the Distro plate. Such as our 6900xt water block kit BP-TEKIT-6900XT, which fits for TITAN One series. Here is the link. You can download the installation guide and see how to connect the GPU water block to the distro plate.
BP-TEKIT-6900XT
https://shop.bitspower.com/index.php?route=product/product&product_id=7953&search=6900x