With the case and drive cages almost a certainty, the question remains the cooling, since the case does not include any cooling, but has huge amounts of space for mounting a number of radiators, although the drive cages will limit my options.

Initial thoughts are that a system with 28 HDD's will make so much noise anyway (each internal drive cage has a 120 mm fan and the hot-swappable Chenbro's have a 80 mm fan at the back) with 7 fans for the drives, the options for Kepler water cooling are currently non-existent, so the benefit of water cooling must, at least for the time being, come from the CPU cooling. It may result in a very slight advantage over air cooling, almost negligent, but will require a tedious installation, is much more expensive and requires more maintenance, so it does not look appealing to me. My initial feeling is KISS, just a Noctua NH-D14 in push-pull configuration. But that means also that for all those possible fans I have to budget a large number of Scythe Slip Stream SY or Noctua NF fans. A separate article is planned on thermal design, where we will examine the pro's and con's of positive and negative pressure and the consequences. Initial preference CPU cooler: Noctua NH-D14 CPU cooler

Initial preference case fans: Scythe Slip Stream SY1225SL 12L (very quiet) or Noctua NF-P12 (because of a high CF/db ratio).