WS2812

Roger Cheng

Shopping for PC Cooling Fans with RGB LED

I’ve decided to investigate controlling the RGB LEDs embedded in aesthetics-based PC accessories. I’m not interested in using them for my PC, but as research for a yet to be determined future electronics project. I wanted something that is a standardized commodity with a large range of variety in the ecosystem and have some usefulness beyond just looking shiny. I settled on 120mm PC cooling fans.

There are many common sizes for cooling fans, but I’ve found 120mm to be the most common for aftermarket cooling. They’re larger than average for CPU cooling, but not too large especially for heat-pipe based cooling towers. But they’re typically installed for general cooling in tower cases, whose cooling vents are cut for 120mm fans. Covering both popular use cases mean more options.

Looking around on my NewEgg, I find that fans sold individually typically have two separate connectors. One for LED and one for fan control. To the rest of the computer, these fans look like two separate peripherals: the LED and the fan. They just happened to coexist in the same device. The fan control connector sometimes just have two wires for +12V and ground. Some have a third tachometer wire for reporting speed, and some have a fourth wire for built-in PWM control. Here’s an example of a CPU cooler the Vetroo V5 whose fan has two connectors: a 4-pin CPU cooler fan control connector and a JRAINBOW RGB LED plug. These should be simple and straightforward to interface.

More challenging are fans that use an intermediate hub. The hub has a connector for power and for JRAINBOW, consolidating those signals into a proprietary connector. I started contemplating this particular Rosewill RGBF-S12001 three-pack of fans which use such a design. I think I can decipher roles of each wire so I could bypass the hub and control each fan directly. This multipack also had a remote control for direct control of the hub without a computer. This is appealing to me, because independent control meant I didn’t need a PC involved as I probed how it worked. If I should make a fatal mistake (say, accidentally short-circuited something) it should only kill the hub or the fan and not an entire computer.

As I scrolled down, though, Newegg showed me several other items under “similar products”. I saw an even more discounted three-pack of fans: the Asiahorse Magic-i 120 V2. Three fans for fourteen bucks, well within my impulse buy range. I’ll buy the pack and see what it does.

Roger Cheng

Repurposing PC RGB LED Accessories

I’m quite comfortable poking around inside the tower case of a DIY PC. I’ve built a few PCs from components, and I’ve bought a few that came prebuilt by a shop. In my PC experience I’ve focused on the functional side of things and haven’t paid much attention to the aesthetics side. There’s a whole segment of the market enchanted with flashy LEDs. As an electronics hobbyist, it had been hard for me to look at those accessories seriously. I know how little addressable RGB LED modules cost in bulk, and it is quite clear those PC accessories were sold at a huge profit margin. I would be more inclined to build my own LED creations like Glow Flow than to pay a premium just for overpriced flashy lights in my PC.

But what if I looked beyond products’ MSRP? Since this particular market is about novelty, just like the clothing fashion industry there is a high turnover of products. The huge profit margin entices startups hoping to make it big, and most don’t. High product turnover means there are those who upgrade to the latest look. Each of these scenarios can lead to products sold well below MSRP: (1) clearance sales on unsold inventory of “old looks” (2) liquidation sales from bankrupt companies, and (3) secondhand markets (eBay/Craigslist) for those who have upgraded. A bargain hunter can find LED-bedazzled gear well below the price of new equipment, and in extreme cases even lower than price of buying new WS2812 modules directly.

Well, now I’m interested! Not for my PC, but for potential future electronics projects. Which means looking at these products and try to figure out how I can repurpose them. I started by looking at the product pages for a few PC hardware component companies and their advertising spiel for RGB LED accessories.

  • Corsair uses the iCUE branding as an umbrella covering aesthetics-based accessories. Some are the addressable LEDs I care about, but not all of them.
  • Gigabyte uses the name RGB Fusion.
  • Asus calls theirs Aura.
  • MSI calls theirs Mystic Light.

I hit a gold mine on MSI’s Mystic Light site, because their FAQ included an entry “What is Mystic Light Extension” that gave the following description:

Mystic Light Extension is a feature of Mystic Light software which allows user to control colors and effects of partner’s product such as RGB LED Strips, RGB PC Fans or RGB PC Case via on-board JRGB / JRainbow / JCorsair pin header.

    JRGB (4-Pin / PIN-definition: 12V/G/R/B): The JRGB pin header provides up to 3A (12V) power supply for non-addressable 5050 RGB LED solution showing single color.
    JRAINBOW (3-Pin / PIN-definition: 5V/D/-/G): The JRainbow pin header provides up to 3A (5V) power supply for addressable WS2812 RGB LED (ARGB) solution showing rainbow color.
    JCORSAIR (3-Pin / PIN-definition: 5V/D/G): The JCorsair pin header provides up to 3A (5V) power supply to Mystic Light software compatible CORSAIR devices.

This tells me products that use the JRGB header are colorful but not individually addressable. Products using JRAINBOW or JCORSAIR are 5V devices that uses a single data pin and no clock. This is a very strong hint these products are made of LEDs made of either WS2812 (“NeoPixel”) or alternatives that understand the same control signals. I will go look for a bargain and try one out.