MIX 1/2 and 3/8 TUBES

I was just thinking, would there be any effect if I use 2 sizes of tubes for my WC? I have a RAD with 1/2 OD/ PUMP 1/2 OD/ CPU block 3/8 OD/ chipset block 1/2 OD. THANKS

IMO, I would just replace the 3/8" barb with a 1/2" one from the hardware store.

The only effect is that the 3/8 section will have more headloss (flow resistance) than the 1/2' section.

I have mixed tubing sizes in my system. The main reason is to match the tubing size to best fit each part (blocks, pump, rad, T) in the system. My blocks are pin-fin type and don't require the highest flow rate to perform decently so having some 3/8ID tubing isn't much of a performance compromise.

The 3/8ID 1/2OD fits the MCW50 block without adapters
The 1/2ID 5/8OD fits the outlet barb (with built-in clamp) of the L30 pump and MCW5002 barbs
The 1/2ID 3/4OD is strong enough to be easily streched over 5/8OD barbs (T-line and L30 inlet) and copper tubing (heatercore tubes)

It's not a common tubing arrangement but it works for me.