Water Cooling Tube Size - Does it Matter?

Water cooling tubing size has long sparked debate in the PC cooling community, and this video revisits the topic with a deliberate, controlled test. The host asserts the common belief that tubing size should not meaningfully impact system temperatures, then designs a proper experiment to verify or challenge that claim. They set up three different inner diameters (ID) of tubing, all running in the same loop with a Fractal Design Define R5 case, a 3/8 inch ID by 5/8 inch OD PrimoChill tubing baseline, and a standard liquid cooling loop including a CPU block, radiator, pump, and reservoir. The testing rig uses a high-frequency stress load (4 GHz, 1.15V) and a flow meter to observe any performance differences across tubing sizes while maintaining consistent coolant and environmental conditions. After thorough 15-minute test intervals with ample warm-up and cooling periods, they compare results and determine that tubing diameter has little to no effect on overall cooling performance, with most observed differences falling within the margin of error. The verdict emphasizes other factors as more influential for loop performance, such as CPU/GPU contact surface, radiator area, and fan airflow, rather than the tube diameter itself. The video concludes with a practical recommendation: stick with reliable tubing in a standard range (3/8ID 5/8OD or 10 mm ID with comparable OD) and consider wall thickness to resist kink during bends, while choosing fittings and blocks that minimize flow restriction. In short, when building a water cooling loop, tubing size matters far less than pump capability, block restriction, or radiator efficiency, so choose quality tubing and focus on overall loop optimization.

Topics · Science & Technology · Hardware & PC Building