Open-Air vs. Blowers
For most of the past 10 years, nearly every new high-end graphics card has relied on some sort of a blower fan for cooling. The first such designs, such as the GeForce FX 5800 Ultra, had a terrible and well-deserved reputation for being too loud.
Jet engines use radial fans— why would anyone want a jet engine in a GPU cooler?
Despite those legitimate complaints, Nvidia and AMD have repeatedly put out reference designs that used blowers with radial fans instead of axial fans and open-air coolers. There are pros and cons to both types of cooling solutions, of course.
Why were blowers desirable? All the information I’ve seen and personal experience confirm that a radial fan is almost always louder than an axial fan that moves a similar amount of air. Axial fans move a large volume of air at low pressure, while radial fans are much higher pressure for the same net airflow. Jet engines use radial fans—why would anyone want a jet engine in a GPU cooler?
There are two major benefits with blowers. The first is obvious: The cooler can serve as an additional exhaust fan for the PC. Considering modern GPUs can easily pull 250W or more, dumping all that heat into the inside of a PC case means you need more case fans to deal with it. But the other benefit isn’t as obvious: The radial fans used in blower coolers tend to be far more durable.
I’ve used and tested perhaps 100 graphics cards during the past decade. I’ve had two radial fans fail that I can recall, and probably dozens of axial fans that eventually needed replacement.
There used to be another potential advantage for blower designs. For a single graphics card setup, the choice between a blower or an open-air cooler didn’t usually matter, but multi-GPU rigs often struggled with open-air coolers. I even tested a couple of desktops with open-air SLI setups that struggled thanks to the cramped quarters—one couldn’t even run stable without cranking the fan speed on the inner GPU to 100 percent. Oops.
Multi-GPU setups were standard with cryptocurrency mining, but mining pushed the hardware in ways it was never intended to handle. Running 24/7 100 percent load computations is more what you’d expect of hardware in a data center, not from consumer graphics devices used for playing games. Data center GPUs, such as Nvidia’s Tesla line, typically omit fans entirely and expect the server chassis to provide the airflow.
Now cryptomining has died down and support for multi-GPU is all but dead, it’s no surprise to see blowers losing favor. In the last year, both Nvidia and AMD have begun shifting to axial fan designs. Nvidia started when it switched to axial fans on its RTX reference designs in 2018, and continued with the RTX Super models this year. AMD also uses a triple-fan axial cooler on the Radeon VII, though it went back to radial fans on the RX 5700 series cards at launch.
In retrospect, that was probably a mistake—the reference 5700 XT runs very loud and hot. The noise levels of the reference RX 5700 and 5700 XT were so significant that I compared them with a Sapphire RX 5700 Pulse that uses axial fans. The RX 5700 blower generated 50.7dB(A) from 10cm with temps of 73 C on the GPU and 85 C on the VRMs. The 5700 XT was worse: 56.8dB(A) and temps of 84 C on the GPU and 100 C on the VRMs. Sapphire’s 5700 Pulse dropped the noise to 44.7dB(A), with temps of 72 C on GPU and 80 C on VRMs.
The only time I’d consider using a blower is in Mini-ITX builds, where the compact dimensions make airflow a concern. For a microATX or larger desktop, I recommend an open-air cooler with dual or triple axial fans. Your ears will thank you, and with a couple of low-RPM case fans, you won’t need to worry about overheating.