Here's a insulation tape shim on my CPU. Rest of air gaps filled with thermal grease and silicon grease.

Heres the 2 submersible pumps modded to be inline

Block is held down by clip and 4 nylon springed bolts

Dry run of rig, notice the frost on cold plate.

Probe on left shows water temps before block, right shows temp of CPU ceramic plate.

This at full load.

Dry run probes in 2 minutes.

Here's the overclock at 31-32C ambient. A refit gave me 19C full load temps but then when I put it back the temps got worse, so best temps were 19C full load and CPU was stable at 1790mhz.

Here's my collection of radiators.