Used mostly for heavy coding, graphics work, VM host (works great for 2-3 dual-core/4GB RAM VMs).
Cooling is a custom single-loop. GPU block (full card) and triple radiator are EK, CPU block and pump/res are Koolance. Tubing is UV-blue Feser PVC, coolant is color-free PC ice. Radiator fans are Scythe Gentle Typhoons and the back panel is covered with sound proofing, so the whole build is very quiet even under load.