System 4 also has a HDD water-block.

It’s easy to install your HDD into this thing. You’ll need a HDD, a thermal pad and four screws:

The thermal pad lies snugly on the electronics PCB:

And then the HDD is fastened to the water-block. The contact between them doesn’t seem to be good:

Well, the tests will show how well this works.

The fifth configuration (System 5) is the third kit plus an AquaBay M3 reservoir.