Review: Fractal Design Celsius+ S28 Prisma

Test Methodology and Performance

Notes

The introduction of our 2020 Test Platform allowed us to start afresh with CPU cooler testing. The new PC features a 16-core, 32-thread AMD Ryzen 9 3950X processor and 32GB of dual-channel G.Skill Trident Z Neo DDR4 memory set to run at 3,200 using the built-in profile.

A Fractal Design Define 7 chassis is configured with its three stock Dynamic X2 140mm fans connected to the integrated hub and attached to a single motherboard header. Coolers are tested using default out-the-box settings, and to intensify the challenge while minimising noise, all fan headers are set to the 'Silent' profile within the Asus BIOS.

When testing liquid coolers, the pump is connected to the motherboard's dedicated AIO header, and the radiator is installed in the roof of the chassis with fans configured to push air up through the radiator and out of the enclosure. Fractal Design's vented top panel is used with liquid coolers, and the sound-dampened solid panel is in place when testing traditional air coolers.

Actual CPU temperature is recorded and we also graph the delta temperature (CPU temperature minus ambient temperature). Last but not least, to give you an idea of cooler acoustics, we use a PCE-318 noise meter to measure overall system noise in both idle and load states.

Performance

Our benchmarks begin with the 105W AMD Ryzen 9 3950X CPU running at stock speeds. We use the popular and open source Blender creation suite to render the taxing Victor scene and record the average CPU temperature from the last five minutes of 100 percent load.

Not all 280mm all-in-one coolers are created equal. Using stock, out-the-box settings, the Asetek-based Fractal is a distant second to its more affordable rival, the CoolIT-based iCue H115i RGB Pro XT. Not a great start for a £190 solution.

Cooling might be below expectations, however Fractal's Celsius range has always had one eye on acoustic performance, and if you're looking for an all-in-one that's calm and composed, they don't come much quieter than the S28 Prisma. You wouldn't know it's there at idle, and you can barely hear it under load.

Upping the ante in a simple manner, we raise the multiplier to 43x on all cores, while increasing voltage to 1.3V. We know the chip can do it, and the bump in juice is enough to push the coolers closer to their limit.

There has to be a trade-off. Fractal's Auto profile may be lovely and quiet, but that doesn't bode well for overclocking, with our 3950X getting dangerously close to the limit. If you're planning to play with higher voltages, be prepared to switch to the PWM profile and set-up your own pump/fan speeds.

Then again, if what you really want is liquid cooling that's quiet, the S28 Prisma with no additional tweaking is insistent on keeping noise levels down to an absolute minimum.