Finally some pics that show a pump mounted on it. It also acts as a heatsink for a DDC. The implication from that page is that you can use a D5 but not directly attached like you can with a DDC - ie it's just a res with an external, separate D5 pump.
http://www.phanteks.com/PH-R220.html (6th picture again in the gallery at the top of the page)