Chad's CPU Cooler Test System Specifications
- Motherboard: ASUS ROG Maximus VIII HERO (Intel Z170) - Buy from Amazon / Read our review
- CPU: Intel Core i7 6700K - Buy from Amazon / Read our review
- Memory: Patriot Viper 4 3000MHz 4X4GB - Buy from Amazon / Read our review
- Graphics Card: MSI GeForce GTX 1060 6GB OC - Buy from Amazon / Read our review
- Storage: Corsair Neutron XTi 480GB - Buy from Amazon / Read our review
- Case: INWIN D-Frame - Read our review
- Power Supply: Thermaltake Toughpower DPS 1050W - Buy from Amazon / Read our review
- OS: Microsoft Windows 10 Home 64-bit - Buy from Amazon
- Software: RealTemp 3.70, AIDA64 Engineer 5.75.3900, and CPU-z 1.77.0 x64
To see our testing methodology and to find out what goes into making our charts, please refer to our CPU Cooler Testing and Methodology article (October 2016) for more information.
At 60.25-degrees, using the S28 in PWM mode, we cannot say we are all that impressed with the near fifteen-degree gap to first place. When we look at coolers ranked higher, we were not fond of the Freezer 33, but at a fifth of the cost of the S28, it looks pretty good now! The specifications being what they are for the S28 Prisma, our hopes were much higher! For those that want to try the AUTO control, add four-degrees to the PWM results, and you will drop into the bottom seven coolers listed!
With the overclock applied, the S28 Prisma is now only eleven degrees from the top of the chart, but that 77.25-degree result of the Fractal, which ties with a $30 to $40 air cooler! The other side of the coin is that we are still twenty-two-degrees from the throttle point. Moving away from PWM to AUTO control, the temperatures jumped six-degrees this time, tying for last place!
As we do, we leave the overclock applied, and let the fans do their best at moving all the air they possibly can through the cooler, and see what is left on the table. With an additional 900 RPM and a ton more noise from the fans, we could only get another 3.25-degrees out of the S28 Prisma, which still leaves it near the bottom of the chart.
Noise Level Results
Under PWM control, with the stock load applied, the fans moved from 500 RPM at idle, to a whopping 540 RPM under load. While Fractal keeps the noise at bay with the 24 dB rating we have them at in our charts, we can see why thermals are what they are. Keep in mind that this is with the pump at 1660 RPM, and in AUTO mode, the pump only runs at 900 RPM!
For those out there who want quiet over performance, even with the overclock applied, the PWM curve kept the fans at just 775 RPM and 28 dB with the overclock used. The pump jumps up to 2083 RPM under PWM control, but on AUTO, the fastest we saw it spin was 1250 RPM.
Forcing 12V DC through the fans allowed them to top out at 59 dB, and with that enormous increase in noise and fan speed, it nets minimal gains to even deal with this level. We did notice that the pump turned at 2710 RPM at this time.
We now understand the point of the 3500 RPM option on the pump. The use of AUTO keeps the noise level between the head unit and the fans similar. Under PWM control, the loudest we got from the pump was 29 dB, but the slower it goes, the quieter it is. So with fans spinning at 550 RPM, with virtually no noise involved, the pump has to slow way down to coordinate with the fans.
In doing so, it allows the potential for a runaway condition, even if the fans are spinning nearer 800 RPM. Rather than blast your ears with the 58dB of noise from the fans in the last-ditch effort to cool things down, the pump spins at 3500 RPM until the liquid temperature returns below 60-degrees.