The MULTIFAN S5 is two 80 mm fans on one controller, permanently joined by a 760 mm (2.5 ft) cord. That is the whole idea: instead of one fan pushing air at a hot box, you can put one fan low to draw cool air in and one high to push warm air out — which is how a closed cabinet actually gets cooler. 52 CFM total at 18 dBA, powered from a USB port, with an in-line speed dial so you can wind it back until you stop noticing it.
Two fans beat one, when the air has to go somewhere
A single fan inside a closed cabinet mostly stirs hot air around. Heat still has nowhere to leave, so the whole space just becomes evenly warm. Splitting the job across two fans lets you set up an actual airflow path — intake at the bottom, exhaust at the top, warm air leaving the cabinet instead of circulating in it.
The other use is simpler: two pieces of gear on different shelves, one fan each, one power source and one dial between them.
Quiet enough to sit in a lounge room
18 dBA is the figure at rated speed, and the in-line controller takes it below that. The dial has a power switch and sits on the cord rather than the fan, so it ends up somewhere you can reach without moving equipment.
Eight anti-vibration rubber feet come with each fan, and they matter more than people expect — a fan resting directly on a hollow cabinet panel turns that panel into a soundboard, which is usually what someone is hearing when they say a quiet fan is noisy.
Specifications
| Manufacturer | AC Infinity Inc. |
| Product / model | MULTIFAN S5 / AI-MPF80A2 |
| UPC | 854759004334 |
| Configuration | Two 80 mm fans, permanently joined, sharing one controller |
| Dimensions (per fan) | 8.0 × 8.0 × 2.5 cm (3.2 × 3.2 × 1.0 in) |
| Hole-to-hole spacing | 7.2 × 7.2 cm, Ø0.4 cm screw holes |
| Total airflow | 52 CFM (26 CFM per fan) |
| Total noise | 18 dBA |
| Speed | 2,000 RPM |
| Static pressure | 1.6 mm-H₂O |
| Operating voltage | 3–7 V DC (USB) |
| Current | 0.38 A |
| Cord between fans | 760 mm (2.5 ft) |
| Power cord | 1.8 m (6 ft) |
| Controller | In-line multi-speed dial with power switch |
| Daisy-chaining | Pass-through USB port — up to four units on one power source |
| Operating range | 0–70 °C / 35–85% RH |
| Bearings | Dual ball, rated 67,000 hours (manufacturer rating) |
| Mounting | Horizontal or vertical |
| In the box | Two joined fans, in-line speed controller, eight anti-vibration rubber feet per fan, 1.8 m USB cord |
| Certifications | UL (fans) · CE · RoHS |
| Product manual | Download PDF |
FAQ
Can the two fans be separated?
No — they are permanently joined by a 760 mm cord and share one controller. That cord length is what decides how far apart you can place them, so measure before ordering if you are putting one fan on each of two shelves.
S5 or one larger single fan?
Take the S3 or S4 if the heat is in one place — a bigger fan moves the same air more slowly and therefore more quietly. Take the S5 when you need air moving at two separate points, which is most closed cabinets and most multi-shelf racks.
S5 or S7?
The S7 is the same idea with 120 mm fans and double the airflow — 104 CFM against 52. Go S7 for a full rack, a hot receiver or an enclosed cabinet with real heat in it. The S5 suits tighter spaces where a 120 mm fan simply will not fit.
Where does it plug in?
Any USB port — most people use one on the back of the device being cooled, so the fans power up and down with it. A USB wall adapter or power bank works equally well. No mains wiring, nothing to install.
Will it pull air through a duct or a filter?
No. At 1.6 mm-H₂O this is a low-pressure fan built to move air across open components. Attach ducting or a filter and the airflow collapses. If the air has to travel through something, you want an inline duct fan instead.
Is this genuine AC Infinity stock with Australian warranty?
Yes. Quick Bloom Lights is the official Australian importer and distributor for AC Infinity. Stock is held in Sydney, orders ship domestically, and the two-year warranty is handled here rather than through an overseas seller.