The LDPCSJ PRISM 4 PRO (also sold as “Upsiren” or “Teucer” depending on where you’re shopping) has become a go-to for builders who want the Lian Li Infinity look without paying $30 a fan. It sits in that rare category of budget hardware that doesn’t feel like a compromise once it’s actually in your system. Here’s everything you need to know.
Quick Highlights
- Virtually silent at idle: 19–21 dB at 600–900 RPM
- Peaks at 28.5 dB under full load at 1500 RPM
- 45.2 CFM airflow drops internal temps by 3–5°C over stock fans
- 2.05 mmH₂O static pressure handles radiator duty surprisingly well
- Nine-blade profile minimises turbulence noise at higher speeds
- Pre-applied silicone pads prevent chassis resonance
- Daisy-chain ARGB and PWM so no hub needed
- Five fans safely off one motherboard header at 0.16A per fan
- Infinity mirror depth effect that genuinely holds up in person
Noise & Acoustics
The “PRO” designation isn’t just a name bump. Cheap fans tend to produce a high-pitched whine that cuts right through ambient noise and slowly drives you insane over a long session. The PRISM 4 PRO is specifically tuned to push that resonance down into a lower-frequency hum instead. The difference in practice is significant. A low hum blends into background noise the way a refrigerator does. A whine does not. It’s the kind of thing that sounds like a minor technical detail until you’ve lived with a bad fan for six months and started questioning your life choices.
At idle the LDPCSJ PRISM 4 PRO sits around 19–21 dB at 600–900 RPM. For context that’s roughly the level of a quiet library or an empty room at night. In a real-world setup with a desk and a monitor and other ambient noise in the room you will not hear these fans at idle. That makes them genuinely viable for workstations that run around the clock where fan noise isn’t just an annoyance but something that compounds over hours and hours of use.
Push them to 1500 RPM under load and they hit around 28.5 dB. That’s audible if the room is quiet but it’s not the kind of noise that pulls your attention. The nine-blade design is doing real work here. More blades mean each individual blade moves less air per rotation which reduces the turbulence spikes that create tonal noise. What you get at higher speeds is a smooth broadband rush of air rather than a mechanical whirring or a high-frequency buzz. It’s the difference between hearing wind and hearing a machine.
The silicone corner pads deserve more attention than they usually get in budget fan reviews. Vibration isolation sounds like an audiophile concern but it has real engineering consequences in a PC build. The motor in any fan produces a small amount of rotational vibration. Without damping that vibration transmits through the fan frame into whatever it’s screwed to and from there into the case panels. Sheet metal is surprisingly good at amplifying and broadcasting that frequency. The result is a low droning resonance that can be louder than the fan itself and is significantly harder to track down. The PRISM 4 PRO ships with thick silicone pads already applied to the mounting corners so that energy has nowhere to go. It’s a small thing that makes a noticeable difference and it’s the kind of detail that more expensive fans get right and budget fans routinely skip.
Airflow & Cooling
45.2 CFM is the number you want to pay attention to for a 120mm fan. Airflow in PC cooling is subject to diminishing returns in both directions. Too low and you’re not moving enough volume to matter. Too high and you’re either running at aggressive speeds that generate noise or you’re selecting a fan so large and powerful it belongs in a server rack. 45.2 CFM hits the efficiency window where you’re moving serious air at speeds that stay acoustically tolerable. In testing this translates to a consistent 3–5°C drop in internal case temperatures compared to typical stock fans which is meaningful headroom for components running sustained loads.
The static pressure rating of 2.05 mmH₂O is where the LDPCSJ PRISM 4 PRO genuinely earns its place in a more serious conversation. Static pressure measures a fan’s ability to push air through resistance rather than just moving it through open space. Case ventilation is mostly open-air work so CFM is what matters there. Radiator cooling is a different problem entirely. A 240mm or 360mm radiator has dense aluminium fin stacks that create significant resistance to airflow. A fan with great CFM but poor static pressure will move a lot of air up to the radiator surface and then fail to push it through. You end up with hot air sitting against the fins rather than moving through them.
Most budget RGB fans fall apart at this exact test. They’re designed to look good spinning in a windowed case and the acoustic and static pressure engineering gets deprioritised accordingly. 2.05 mmH₂O is competitive enough to run the PRISM 4 PRO on a liquid cooling radiator and have it perform meaningfully rather than just aesthetically. That opens up a lot of build configurations where you’d otherwise be looking at spending significantly more per fan.
Four-pin PWM control rounds out the cooling story. The motherboard reads your thermal sensors and adjusts fan speed in real time to match what’s actually happening inside the case. The fans only spin as fast as your temperatures require which keeps noise down during light loads and ramps up responsively during heavy ones. It’s standard on better fans and it’s here. Worth stating because plenty of fans in this price bracket are still three-pin DC which gives you cruder voltage-based speed control and less precise thermals.
Electrical & Build
The daisy-chain implementation is one of the cleaner cable management solutions you’ll find at any price point. Both the ARGB lighting signal and the PWM control signal pass through from one fan to the next via a built-in connector on each unit. You plug the first fan into your motherboard’s ARGB header and PWM header and then connect each subsequent fan to the one before it. No hub required. No extra cables running back to the motherboard or to a controller box. In a mid-tower with four or five fans in it this is a meaningful quality of life difference. Clean cable routing has real airflow implications and it makes the build significantly easier to work inside later.
The power draw numbers are worth spelling out because they change the planning conversation for larger builds. Each fan pulls approximately 0.16A. A standard 4-pin fan header on a modern motherboard is rated for 1.0A. That means you can run five LDPCSJ PRISM 4 PRO fans off a single header without approaching the current limit. For a typical mid-tower setup with three intake fans and two exhaust fans you can potentially run your entire fan array from one header connection. That simplifies wiring dramatically and removes the need for a splitter or a fan controller in most builds.
The infinity mirror effect in the center hub and surrounding frame is the headline feature and it delivers. Multi-layer mirror construction creates the impression of depth extending back through the fan indefinitely. Photos of it tend to look like renders. In person it has the same quality. The effect is consistent across the RPM range which matters because some cheaper implementations flicker or distort at lower speeds when the lighting controller struggles to keep up with the rotation. These don’t. The RGB itself is bright and evenly distributed with good colour accuracy across the spectrum. If you’re building something with a window panel and a colour scheme to maintain these earn their place on that axis alone and then happen to also perform well technically which is a better order of priorities than most RGB-first fan purchases end up going.
For the price per unit the combination of acoustic tuning, static pressure capability, clean cable architecture and a lighting implementation that actually looks premium rather than budget is unusual. These are not perfect fans. If you need maximum static pressure for a high-resistance water cooling loop with thick radiators you should be looking at Noctua or be Quiet. If you need the absolute acoustic floor of the market for a near-silent build the dedicated options from those same brands will edge ahead. But for a builder who wants a fan that handles every part of a normal build competently, looks exceptional doing it and doesn’t cost the kind of money that makes you feel the purchase for a week, the PRISM 4 PRO is difficult to argue against.
Where to Buy
UK: //s.click.aliexpress.com/e/_c2IPgER1
Western Europe: //s.click.aliexpress.com/e/_c3BDmyNd
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USA: //s.click.aliexpress.com/e/_c3iPzQs7
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