Cooler Master V850 SFX PSU Fan Swap


Minimal Tinkerer
Original poster
New User
Jul 30, 2020
Hi, this is my first post. I wanted to show a fan swap for this Cooler Master v850 SFX PSU. I looked online before doing this mod and found very limited info on it.
This particular PSU is of interest because it is the highest wattage SFX unit currently available. The 1000W unit from silverstone is double the price and SFX-L anyways.

The version I have with with the update temperature dependent fan curve. The earlier units were reported to be annoying because they ramped the fan from 0 - 100% based on load, but newer units do not have that behavior, so this mod is for the constant low RPM noise. I found that the stock fan on this product is pretty loud at low speeds, especially when I compare it to the Corsair 750W unit I had used previously.

  • Cooler Master V850 SFX PSU (make sure its the revised temperature based fan curve)
  • Noctua NF A9x14, I used the chromax black version
  • 2 pin to 4 pin fan adapter. this is the specific product I used.

Disclaimer - Obviously this voids the warranty and its dangerous to poke around the inside of a power supply.

First I unscrewed the top of the PSU and unplugged the original fan. This is a picture of the 2-pin fan connector.

Then I unscrewed the default fan from the top panel and replace it with the noctua fan. They are the same size (92mmx15mm) and no extra work to attach the new one to the top panel. I made sure the corner with the fan cable is close to the corner with the 2-pin fan header. This was important for fitting it together later.

The V850 SFX is very dense and there's not much extra space inside. In order to plug the 4-pin PWM noctua fan to the PSU, I had to use the 2-pin to 4 pin adapter. The connector for this adapter is somewhat bulky, and I had to find a space for it inside the PSU. Luckily, there is this small void right next to the fan header which can fit the connector on the adapter cable.

In this image I am pointing at the location of this void where I had to make sure the connector was stuffed into before closing the unit.

Here is the picture of the connection from the fan -> 2 pin adapter. I put electrical tape around it because the fit was loose and actually came unplugged the first time I closed the unit.

By default, the nocuta fan's cable is attached to the outside of the fan's frame by a small plastic tab. This made it impossible to position the connector inside the PSU's empty space. I cut out this tab on the edge to free the cable and get a bit more maneuverability for the cable.

Finally, I re-attached the top lid of the PSU. As I am about to close it, I check to make sure the adapter's connector is sitting inside the little void.

When the unit is sealed up, I did one last check to make sure the fan spins freely, and did not get blocked by a cable or the 2 pin adapter's connector.

Finally, here is a comparison of the stock fan and the noctua fan.

Result - I ran furmark to cause the PSU temperature to increase. After some time, the fan seems to spin up just fine. Compared to the stock fan, it is basically inaudible over the rest of my system.


What's an ITX?
New User
Jan 20, 2023
i boght that same psu and that fan noise is so loud. i think i do same mod that u did yours. Thx for sharing this! do you think that i can solder that old cable to new one because i live in finland and amazon was only place i find that adapter and posts are 15 dollars to finland :(