ARCTIC S4028-15K - 40x40x28 mm Server Fan, 1400–15000 RPM, PWM Regulated, 4-p...

I picked up one of the 6,000rpm variants of these fans to aim at the 12VHPWR connector on my RTX 5090—you know, just to be safe. I even 3D printed a little right-angle duct adapter to funnel air down over the connector itself. Ultimately, I ended up removing it from the system because I found the noise output unacceptable, even at very low operating speeds. ➤ The Challenge with 40mm Fans 40mm fans can be tricky with noise. Twenty to thirty years ago, 40x10mm was a common size on chipsets and video cards, and I've had quite a few fans in that form factor that were essentially inaudible when installed in a case. I've also had other 40mm fans—like these Arctics—that produce specific tones that pierce through just about anything you mount them to or in. In terms of quantitative noise levels, these are very quiet fans for what they are. I have some 40mm Sanyo Denkis on a 2.5" drive cage that are audible across the house even at 7,000-9,000rpm; these Arctics are nothing like that. Qualitatively, however, the noise these produce is specifically irritating to me. I can sit next to the server with those Sanyo Denkis screaming away and after a few minutes stop noticing them (arguably because after a few minutes I've gone deaf, but...). The single Arctic I had on the 5090, running at <2,000rpm, was obviously far quieter but also far more irritating in the way it was *just* audible over the rest of the system. Unfortunately, despite the flow straighteners, at <2,000rpm it didn't move a meaningful amount of air for my use case, meaning it was essentially added irritation for no reason. It's not that they're loud—it's that the specific tone they make, even in the context of what they are, is particularly grating to me. Your experience may, of course, differ. ➤ Use Case Matters For their intended use case (in a 1U server), these are extremely quiet and highly power efficient. For use in a desktop, however, they become meaningfully audible far before they move a meaningful amount of air. Unless you have a specific need for a 40mm fan, you would generally be better served finding an alternative way to accomplish whatever task you're considering these for. ➤ Bottom Line I can't and won't knock any stars off the fan itself—these earn the full five stars easily. They're power-efficient, quiet for what they are, dual ball bearing, exceptionally well-built, and Arctic provides actual performance data including P/Q curves and PWM curves. Both are generally absent with consumer-grade fans and are hugely useful if you know how to read them, signaling that Arctic is serious about selling these for actual industrial/server use. But for the home/enthusiast/desktop user, these are clearly audible well below 2,000rpm and essentially unacceptable over 3,000rpm. If you have a specific need for them, I'd recommend them. If you can accomplish your goal with a larger fan, you'd probably be happier going that route.

I have bought multiple packs of the 6K and used them all over. Imo I would say the difference in noise between these and a Noctua is fairly neglible so don't believe those that say these are insanely loud. I may be biased because I am replacing MUCH louder fans in old server equipment so anything quieter is a blessing, however I have tested the Noctua and the 6K version side by side in a quiet computer room of mine and even being next to them on full blast these were barely audible. I hooked them up to a bench top power supply giving 12V DC so there was no confusion of if they were each on full blast or if the noise was being muddied by other fans. I think the Noctua is a better pick if you absolutely value complete silence above all and you intend to use these in a computer that you have tuned to full blast. Otherwise with PWM I would pick these 100% of the time - they're much cheaper AND they move MUCH more air than the Noctuas, which is another great benefit in old server components -- I need the airflow. Ultimately these are a great buy and I would definitely recommend them!

These are amazing 40mm fans, and move a ton of air. I use them to cool several Tesla P40 GPUs with custom 3D printed shrouds and 2 fans per card, and they do an amazing job keeping them cool under load. They are loud, but at 50% speed the noise isn't too bad and they still cool really well. Probably could've went with the 6K model but I wasn't sure what temps I would get so wanted the extra overhead just in case, and knew I could run these at lower speeds anyways. Given the small price difference you might as well get the 15Ks and run them lower. Overall these were a great buy.

No frills, no marketing bs, just pure performance. I needed good 40mm PWMs to cool my optane rams and these were perfect. I would have gotten the normal AVC used in servers but they're too loud. The 11k RPM version of this would work just as well and is also quiet compared to the AVC but it was not needed for this use case. The rams were hitting 70c prior without proper airflow. They peak at 43c with these fans mounted on top.

This fan offers pretty good cooling for the size, but as other reviewers have mentioned, it is quite noisy when kept at close range

I got the Jonsbo TK-1 v2 case, but there weren't a lot of rooms for larger 120-140 fans. BUT THESE BAD BOYS CAME IN CLUTCH. There's some ventilation space on the left side of the case that I suspected these could fit in, AND THEY DID! Helped reduced my temp by quite a lot, I can feel them pumping out air as I ramp up performance and they do AN AMAZING job. The YouTube videos on them were rare albeit high quality and that's why I decided to stick with them instead of competitors. Running 4090 and 7950X3D and mewmaxxing on ultra + high every settings on Baldur's Gate 3 and Dota 2, but temps after were fantastical. Obviously water-cooling is a component here, but these fans did WORK to keep the internal of my chamber breezy. Will be buying more and stocking up for future builds. 10/10 🔥

They work great. Much quieter than normal delta fans.

Item arrived in good condition. The fan is very strong but very loud too. However, the airflow is strong too. But the noise level is loud if at max rpm. It sounded like medium to high pitch whistle type.

El performance de los ventiladores es muy bueno definitivamente cumplen con su función, tanto para servidores, NAS o para agregar un extra de ventilación a los headsync de la tarjeta madre funcionan a la perfección, el flujo de aire es bastante bueno y con bajo nivel de ruido. en comparación con la competencia NcTua, creo que valen cada peso de lo que cuesta el paquete de 5 es excelente y son PWM

I bought 2 of these fans to use in my remote control vehicles. I had to convert it to a 3 wire plug, (YouTube has a video using these fans) but they really pump the air and keeps my motors a lot cooler when bashing on my trucks.