maximumpc.com DEC 2019 MAXIMUMPC 15
Jarred Walton
TECH TALK
Jarred Walton
TECH TALK
Jarred Walton has been a
PC and gaming enthusiast
for over 30 years.Open-Air vs. Blowers
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
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.
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
R X 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 theVRMs. 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.Jet engines use radial fans—
why would anyone want a jet
engine in a GPU cooler?
The reference RX 5700
cards may mark the end
of the blower cooler era.