Just saw your post ... I have a Z840 that I have upgraded to E5-2667v3 processors. Those consume 130 Watts each so I wanted to upgrade to liquid cooling basically to find out it was not available. But on closer look, I noticed that the Z840 motherboard had similar pin connectors (and in the same location) for liquid cooled heatsinksas my Z820. The only difference being the Z840 has a 3-pin header while the Z820 has a 4-pin header. The liquid cooled heatsinks for the Z820 have a 4-pin plug but only three have wires in them. So I decided to install them on the Z840 and connect the 4-pin plug to the 3-pin header leaving the empty header position off to one side (blank). AND, they work!
The fans showd is no problem since it is the same as in the Z820 ... So I am running a Z840 with liquid cooled heatsinks.