3\8" ID - 5\8" OD (10-16mm) Or 3\8" ID - 1\2" OD (10-13mm) This will be my setup Asus Rampage IV Extreme Koolance RP-452X2 Dual 5.25 Rev 2.0 Koolance PMP-450 High Flow Pump : PMP-450 Cpu block not sure what one to get? EK FB KIT RE4 CSQ Motherboard Waterblock Acetal EVGA Hydro Copper Waterblock for GTX 680 Classified Alphacool NexXxos XT45 360mm Triple Radiator Alphacool NexXxos XT45 480mm Quad Radiator Motherboard and cpu will have 90 Degree Rotary Fitting`s to cut down on the clutter .
Personally I'd go with 3\8" ID - 1\2" OD (10-13mm) - they are slightly more common so should be easier to get hold of in the future if you need to expand your loop
Just gonna say I'm madly unimpressed with koolance equipment, I've had 3 blocks that all deteriorated on the insides filling my loops with crap and several bungs that also deteriorated and leaked everywhere, I'll never ever use koolance again. I'd stick with other brands, ek, phobya , alpha cool etc Cpu block I'd go with a swiftech Sent from my GT-I9505 using Tapatalk 2
I've used 3/8"ID, 1/2"OD and for a simple loop they're fine. I prefer 3/8"ID, 5/8"OD though as you get a better bend radius without kinking compared to the smaller size. XSPC Raystorm blocks have good cooling performance with less restriction than many other blocks. Swiftech compressions are good, the silver finish ones have a layer of chrome so have a bright shiny finish similar to Bitspower.