AC Infinity MULTIFAN S3, Quiet 120mm USB Fan, UL-Certified for Receiver DVR PlayStation Xbox Computer Cabinet Cooling

The AC Infinity 120mm fan is a solid & quiet cooling fan. I needed something to place either near or on top of my Firewalla Gold as it gets very hot at times and I wanted to see if something could be done to cool it down with zero noise. For $14 I decided to give this well-reviewed cooling fan a shot.Long story short, this fan works flawlessly. It checks all the boxes. Silent running. Multiple speeds (I keep mine on the lowest as that is all that is required to bring the Firewalla cooling fins down to room temp or lower). Inexpensive. I have a router right next to the Firewalla so just used the USB from that for power but any USB type A will do.I also purchased their 80mm dual fans as well and using those on a Comcast Cable X1 box that gets hot in my entertainment center. These help move the hot air out of the semi-enclosed space the box is in.

Update 3/2018: Expansion of the home network to include a home office resulted in another cooling fan for my crowded computer center (converted credenza, snug). The newest AC Infinity now has a variable speed switch, and costs less. Cabinet temps seldom exceed 5-7 degrees over the ambient room temp. The 120mm seems to be the best fan for the money.Original review:Small, but not so small that it can't move air.QUIET!EffectiveOnce "installed" (more like placed in a cabinet), they are set-and-forget.I purchased 2 of these, being unsure att eh time how effective they would be in a renovated office credenza-become-computer center.Within the top half of this cabinet space, just under 3 cubic feet (9"h x 18"d x30" w) I have a satellite modem (runs very warm), 2 routers and a switch, and a desktop refurbished as a firewall.Before stuffing all these components into this space, they occupied the lower half of a bookcase that sat atop the credenza, and all were clearly producing heat. Therefore the notion that these AC Infinity fans (or similar) would be required inside the smaller credenza space.I started by placing one fan in the rear of the cabinet to push air (cool air from below) across the very warm sat modem and router out to the front of the open cabinet, and there I placed fan #2 to help pull warm air out and into the room.Both fans run exceptionally quiet, and I needed to check occasionally to reassure myself they were still spinning. There is a subtle movement of air as well, not a breeze; simply lick the back of your hand and hold it 2 feet away and you will notice the cooling effect on your skin (an old IT "procedure" for detecting failed equipment fans, always works if not sometimes salty).An indoor/outdoor thermometer served as a great way to measure temps outside the credenza and deep inside (placing the remote temp sensor near to the warmest component, the sat modem in my case). For 2 days the interior cabinet temps remained within 6-9 degrees of the room temp.So I removed fan # 2 (front of the cab opening), all without more than 1 degree increase resulting.Bottom line: small but moves air (don't expect a whirlwind or obvious breeze, it's pretty subtle), and very quiet.The rubber feet on all corners eliminate any vibration noises or humming, and also keeps the fan from moving anywhere.The alternative might be the AI-MPF80A2 dual 80mm fans (52cfm total) if space is an issue.If heat is more of an issue than what I described here, consider the AI-MPF120A2 dual 120mm fans, 104cfm total.Depending on how my single 120mm handles heat this coming summer, I may opt for this dual 120mm fan setup.As for the optional fan thermostat and speed control, I simply let my fans run off any available USB port and do their work.Recommended, keeping your gear cool (or not hot) at this price is great insurance.

The fan came fast and was packaged well. It was easy to use, simply connect the usb to power. It has 3 settings, low, medium and high. Even on the lowest setting it moves the air and cools noticeably. This fan is quiet even on the highest setting. It came ready to be daisy chained so a second fan would be simple to connect. It can stand on its own and can be positioned a multitude of ways while remaining operational. It consumes very little power. I have connected it to my power bank and it goes well over a day before I have to think and recharging my power bank. I am happy with my purchase and I plan on purchasing a second one.

Modem regularly overheated on a poorly ventilated shelf - until purchase of this fan. Quiet, reliable, and effective - solved my concerns about heat-induced reliability issues or shelf damage. Device is practically cool to the touch, now. However, I put it on the bottom, not the top like the illustrations. But I'm sure both work.

In June 2017 I purchased the MULTIFAN S3. I wanted an external fan that was extremely quiet, had an RPM adjustment switch, had vibration dampening feet or pads, and was USB-powered. The intended use was for cooling a vertical/upright Asus RT-AC56U/RT-AC56R router. The average temperature of those routers, with both 2.4GHz and 5GHz radios enabled, tends to be quite high (90C is common, especially during summertime). I also didn't want to void my router warranty modding it to support a fan (not to mention, small fans tend to be high RPM to make up for their size, thus loud -- no thanks!).The MULTIFAN S3 did exactly what I wanted. On medium speed, it's basically inaudible ~4 feet away. At medium speed, it lowered temperatures by about 10C, simply blowing air across the router from the side. The screenshot I've attached shows before-and-after; before, temperatures peaked at ~75C. With the MULTIFAN S3 in place, peaks hit 65C. Excellent for low-RPM, purely external cooling!I used this setup for about 9 months, until one day I began to hear a very quick and occasional "rattling" noise coming from somewhere near my networking equipment (all of which is fanless, excluding the MULTIFAN S3). This noise became more regular over the course of a few days, allowing me to track down the source: sure enough it was the MULTIFAN S3. Most likely the dual ball bearings were gradually loosening (shifting too much inside of their tract/sleeve), or possibly had developed "clotting" of bearing lubricant, both of which can happen with prolonged use.I disconnected the MULTIFAN S3 until earlier this week where summer temperatures were beginning to kick in again. Within an hour of hooking the fan back up, the "rattling" and "clicking" returned, no matter what speed the fan was set to. Bummer. I don't think I got a lemon, as it worked fine for many months. This problem with ball-bearing fans is common even with high-end PC case fans. It's one of the reasons I prefer Noctua oil pressure bearing (SSO/SSO2) fans, but Noctua doesn't make a product like the MULTIFAN S3 without use of third-party adapters.On the subject of fan bearings and lubricant: like most consumer fan products, the MULTIFAN S3 *does not* offer a convenient way to repair, replace, or re-oil the bearings, as there's a very firm plastic or aluminium company logo over the centre spindle on both sides of the fan. And even if there wasn't, many of these types of fans on the market have sealed plastic enclosures so you can't access them anyway, forcing you to buy a replacement.Overall I give this product 4/5 stars because it definitely does everything advertised and AC Infinity should be commended on their product. Just keep an ear out for any bearing problems.