SilverStone AP181 180mm Fans Review – Vortex Airflow

Optimizing Case Airflow

A long time ago, I set out to change how airflow works on the PC. In short it was successful, but not nearly enough to make any important difference. However, SilverStone cued me in on the fact that focused airflow fans can perform better for cases. The design is called a vortex, which the AP181 fans use in a large 180mm diameter for optimal case airflow. They asked me if I would like to test the fans in my own AFX (Airflow Extreme) case I recently built.

With six 200mm fans, airflow is going to be great regardless. My case intakes air from the bottom, and exhaust it at the top. However, a more directional effort can help not only supply further airflow, but help further reduce minor turbulent air currents. That said, it only really matters if it keeps temps lower. In my previous video, there was little cooling difference between my crazy fan design and a Cooler Master H500P with just the two front fans. I’ll say right now that if we see any improvement, I expect it to be minor.

SilverStone AP181 – Vortex Design

Let’s analyze why the AP181 design works so well at directing airflow. As you can see from the images above, a typical fan design is dispersing the air in a large funnel shape from the fan. It makes the air look like it’s more or less sitting there, rather than moving like we’d want it too. On the vortex design, we see a much more focused tunnel, as well as much stronger looking airflow. The way this works is surprisingly simple when we see how SilverStone designed the AP181.

SilverStone AP181 Fans Airflow Test

As you can see, the braces running from the center of the frame to the outside edge are curved. In particular, they are curved in the opposite direction of the curve of the fan blades. This is the key to the vortex design. All a fan blade does is literally push the air in a direction. However, the spinning motion creates a centrifugal force that causes the air to push more at an angle, instead of straight up. Something has to redirect the air and that’s exactly what the counter curves on the braces are doing. As the air molecules are bounced off the vortex frame, the flow is redirected to be almost completely straight up, instead of at an angle.

SilverStone AP181 Install – Features

Even though 180mm is smaller than 200mm (math, right?), the AP181s take larger install spots than my previous NZXT fans. That’s simply due to the square versus round design, but it did mean creating new screw holes for the install. On a wood case, that’s no problem. On a metal case though, you would need mounting holes that are ~250mm apart diagonally. Most 200mm+ fans use a circle frame, meaning the mounting holes will have the same dimension diagonally as the fan. Realize that even though these fans are only 180mm, the mounting is likely to be larger than what almost any case, short of SilverStone specifically, can accommodate.

Outside of the vortex design, the fans are pretty much like other high quality fans. SilverStone used quality feeling plastic for the AP181 which makes them seem sturdy. However, the cables are bit old school. Even though there’s black sleeving on the majority of the cable lengths, the bright yellows and red show at the worst points. As you can see, the cable really shows on the frame and at the end of the wires. On the plus side though, the AP181 has a 3 speed switch to choose between better airflow or better noise levels. In the future, I would love to see this design come to a round, 200mm fan with black wire. (Maybe even RGB!) This would make the fans compatible with a wide array of cases. On top of that, it would clean up the aesthetic a tad.

Test System – Results

Let’s begin with the system and testing method.

  • AMD Ryzen 1800X CPU
  • Gigabyte Aorus X470 Gaming 7 Motherboard
  • 2x Sapphire R9 290X Graphics Cards
  • Crucial MX500 SSD
  • AFX (Airflow Extreme) or Vortex Case (Haven’t decided on a name.)
  • NZXT E850 PSU

In order to push the normal use temperatures to their max, I used the game Rise of the Tomb Raider. I don’t know what it is about the new Tomb Raider games in general, but they always generate the most heat. I even tried Far Cry 5 and Strange Brigade to see how they compare. RotTR is still the best of what I have. I sit Lara in front of a campfire, let the system heat up for 10 minutes, then monitor the average temps for 20 minutes after that. I use HWInfo to pull numbers from the CPU core, the VRMs, the GPUs, and the SSD. At the end of the test, I have to just look at NZXT CAM software to see what the PSU temperature is. Halfway through the 20 minute run, I pull a sound level test using an app on my phone.

I mentioned earlier that I didn’t expect crazy results from the test. I didn’t say this because of knowing before hand what the testing results were while writing. This was exactly how I was feeling before I even got to the testing of the fans myself. As it turns out, my suspicion was confirmed. However, this was really good news in my opinion as well. Most of the components had a minor 1 degree variance. The trade offs were pretty even, except for the second GPU. A 2 degree drop isn’t huge, but we already knew that when 200mm fans are concerned, diminishing returns are a given. That temperature change is actually pretty huge considering the circumstances.

Also, I refused to test the fans at their max speed. I know we could have shaved off an extra degree or two, but the noise levels would have been intolerable. The whole point of this test is to show a fair comparison. At the same noise level, the SilverStone AP181 is performing better than my NZXT fan. What’s important to remember is that the fan blades themselves are still 10% smaller, while performing better. Vortex designs are great for intake case fans, since they make a smaller fan perform far better for the case. Let’s wrap this review up.


In the end, my entire AFX experiment wasn’t a huge success. It does offer great cooling potential, but nothing more than standard cases with large fans offer. However, I love the look of the design at the very least. In fact, it would even make a great layout for a wall mounted display case in my opinion. The SilverStone AP181 fans perform amazingly well. The vortex design focuses the airflow through the case much better, and the design quality is great. However, the aesthetics are bit dated in our market and outside of SilverStone cases, functionality will be very limited without a bit of modding. Pricing is good, but 200mm fans are too competitive for this fan to stand out.

That said, the AP181’s performance really excites me about a new case SilverStone has in the works. At CES, I got the chance to meet a new Raven prototype. It turns the motherboard 90 degrees to vertically mount the GPUs. Even though the design isn’t new for the company, it was the first I’d seen of it. With vortex fans blowing at that angle on the graphics cards, I think cooling will be great. Hardware Hounds is set to look at that case when it releases if all goes well. I can’t wait to see temperature results on that design.

In the end, the SilverStone AP181 Vortex Fan is a great high quality fan. It doesn’t stand out in certain areas to give it other awards, but it excels above nearly every other fan in airflow. We proudly award SilverStone the Hardware Hounds Great Performance Award!

HWHounds Great Performance Award

SilverStone AP181 Vortex Fan

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