Have you booted up your Dreamcast recently for some old-school fun and found that the loud fan noise was a little too much? Maybe your fan no longer works due to age?
This mod aims to solve both issues, with a very high quality Noctua 40mm fan.
Looking at the table below, it’s no surprise that this mod is popular among the Dreamcast community. Running at exactly half the speed of the original fan, the Noctua still manages to outperform the stock fan in every way.
Fan Comparison
| Noctua NF-A4x10 5V | NMB 1204KL-01W-B49 |
|---|---|
| 40mm | 30mm |
| 17.9 dB(A) | 23.0 dB(A) |
| 0.25 Watt | 0.7 Watt |
| 0.05 Amps | 0.2 Amps |
| 4500 RPM | 9000 RPM |
The Adapter
As the original fan is only 30mm, you’ll need to get an adapter to be able to fit the new 40mm fan in its place. That’s where 3D printing comes in. Greg from Laser Bear Industries was the original designer for this mod, and you can purchase it here for a cool $10.
If you have the means, you can also 3D print it yourself from the files on Thingiverse.
Can we make it quieter?
You can! If you would like that “almost inaudible” experience, I have a solution for that.
The NF-A4x10 5V unfortunately doesn’t come in a “ULN” variety, which is Noctua’s lineup of fans that ship with a small adapter to lower the speed of their fans. Fortunately, we can use an in-line resistor to recreate that solution on our own. More on that later once we get to the wiring.
Parts List
| Item | Quantity |
|---|---|
| Noctua NFA4x10 5V | 1 |
| Laser Bear Fan Mount Kit | 1 |
| 10k ohm, 1 Watt Resistor | 1 |
| 16 ohm – 5 ohm, 1 Watt Resistor (Optional) | 1 |
Tool List
- Phillips Head Screwdriver
- Soldering Iron
- Solder Flux
- Solder Braid/Wick
- Solder
- Flush Cutters
- Wire Strippers
- Heat Gun/Lighter
- Shrink Tubing
Step 1: Disassembly
Remove the modem from the side of your Dreamcast by pressing in gently on the tab at the bottom and pulling outwards towards the side.
Then, remove the 4 screws holding the top case on.
Unplug the fan, and remove the 2 screws that hold it in place. You can then pull out the old fan.
Step 2: Wiring The Noctua Fan
It may vary by model, but in my Dreamcast the wires were Orange, Blue, and Red. You can see in the photo that Pin 1 is at the bottom, and Pin 3 is at the top. 
Snip off the connector of the original fan, and strip the wires. We’re going to re-use this connector with our new fan.
You’ll also have to cut off the connector of the Noctua fan, and strip those wires back. At this point it would be best to put a small piece of heat shrink over each of the three wires, and if you want to make it tidy afterwards, a larger piece of heat shrink over the entire thing. That way you can insulate each wire, and also get that completed “stock” look when you’re done.
IMPORTANT: Install a 10k ohm resistor that bridges the 5V line with the Signal line, to increase the power draw of the fan. If you don’t do this step, your Dreamcast will either boot for a few seconds, then shut itself off, or fail to turn on at all.
Wire it up correctly using the pinouts below, making sure that you connect 5V to 5V, Ground to Ground, and Signal to Signal. Don’t worry about the mismatched colours. If you want to lower the speed of your fan below the rated 4500 RPM, see below.
Pinouts
| Dreamcast Fan | Noctua Fan |
|---|---|
| Pin 1: 5 Volt (Red) | Red: 5 Volt |
| Pin 2: Ground (Blue) | Black: Ground |
| Pin 3: Signal (Orange) | Yellow: Signal |
(Optional) Lower The Fan Speed
If you’d like to lower the speed of your fan and trade off a little performance, then you can solder in a resistor between the 5V line and the signal line.
You can play around with the resistor values a little bit on your own, but the general consensus is that somewhere around 16 ohm to 50 ohm ohms will do the trick. As you go higher on your ohm rating, it will result in a slower fan.
Make sure you use a 1 watt resistor or higher, as the resistance will (of course) build up a little heat, and you don’t want to overload the resistor and burn it out.
Step 3: Install the Fan Adapter
Included with your kit should be a few parts. We’re just going to worry about the fan adapter itself for this step.
The adapter will screw into place right where the old one was. With mine (maybe a 3D printing variance), the one little tab was making contact with the optical drive parts, so I ended up trimming it a little bit with a knife.
Once your adapter is screwed into place, you can use a single fan screw to install your fan. There should be some fan screws that came with the fan.
Step 4: Install The New Latch Mechanism
The new fan will make contact with the stock latch mechanism, so you’ll need to replace it. Assemble the parts as shown in the image here, and install it. It’s quite self-explanatory, but you can reference the images here if you need.
That’s it! Check the action on your new latch mechanism, and make sure it functions correctly, and you’re done! Enjoy the new fan performance and noise levels, it truly is a game changer.
Good luck, and I hope this simple how-to was a help to you.
If you have any questions or concerns, please comment below, and I’d be happy to help.
Below is a comparison of the fan noise with no additional speed-lowering resistors applied.
Oh… Hello There Beautiful.
Thanks for reading.
I hope you enjoy what you find on my site, and I will do my best to keep the content flowing as long as I can. Please feel free to comment anywhere on the site, as I would love to hear from you.
– raskulous
Thanks for the detailed instructions. Actually, I found an affordable 3D printout already including the cable with the resistor put into place and a plug adapter. All tools needed was a little screw driver. So 20 years after production, the Dreamcast is finally as silent as it should have been. Absolutely worth the money and it’s completely reversible.