Outdated: see http://www.overclock.net/t/1369708/compact-splash-owners-club/640#post_19823827 for most recent charts.
I updated the measurements for ATX24 connector. This would be the most compact possibility leaving enough space for tubing running underneath. Word to the wise: if you follow this chart, check first using pieces of spare sleeve and with tubes installed.Outdated chart, values are good but unrefined (Click to show)
How to read chart (Click to show)
This chart represents the PSU and MB connectors. At the top is the connector as if you are looking at the PSU, imagine the connector clip on the top. At the bottom is the connector as if you are looking at the motherboard with the ram nearest you, the connector clip is towards you. So on the PSU side, the top left pin is 24, top right is 13, the second row has pins 12 to 1. On the MB side the pins are reversed: top row is pins 1-12, second row is 13-24.
Edited by WiSK - 4/24/13 at 1:32am
Now the numbers in the chart. On the PSU-side they show which wires go where. For example, the blue pin has the number 14, so it goes to pin 14 on the motherboard side. You can see this one is also blue. The number shown on the MB side is the length. So e.g. when wiring that 'blue' wire, you first cut 198mm length, attach PSU-side to pin 14 and MB-side to pin 14. Or e.g. for pin 23 PSU-side, you'd see it goes to pin 4 MB-side, which shows 158mm. And so on.