Fractal Lumen S28 RGB AiO Liquid Cooler Review

Testing

Testing with our FLIR Thermal camera reveals the rather unusual flow path of the Lumen RGB radiator. This is sped up to 16X real time but shows the heat soak across the radiator.

Cool water is pumped out of the hose in the center, is heated by the block, and returns. Upon return, flow is split to the top and bottom third of the radiator, although the bridge around the outlet port seems a hair restrictive as the third closest to the inlet tube gets more of the warm flow. Flows then recombine in the middle third and return to the pump.

Testing was conducted at an ambient temperature of 22C or 72F. Testing is about an hour of an OCCT stress test, and the temperature is logged with HWiNFO. Before we start a stress test, we let the system idle for about half an hour so that everything running in the background finishes up.

We see idle temps averaging around 34C. Not the coldest we’ve seen, but certainly quite acceptable for a 12-core chip. FLIR shows about a 1C delta across the radiator with it being about 2-3C above ambient.

After running the stress test, we see the cooler reach equilibrium in only a few minutes and level out around 65C with the hottest CCX hitting 75C.

Next, we ramp fans and pump to 100% speed and re-test. This time temps average around 53C with the hottest CCX not quite hitting 62C. At 100% speeds, the fans are audible on an open test bench, but not very offensive. We never could hear the pump at any point in testing.