Hi!
Please excuse my english, as it is not my native language. I just would like to introduce myself to you with another RIGOL DHO80/900 fan mod, hoping not to bore you.
As my alias adumbrates, I am an absolutely beginner to more complex electronics. But with general technical knowhow, programming skills, some craftsmanship skills and the will to learn, it was only a matter of time to get an oscilloscope for my Arduino stuff.
What do I want to do with an oscilloscope?
- Analysing the quality of power supplies in my Arduino projects (ripple, noise).
- Analysing I2C stuff.
- Some things I am not aware of yet...
Why the DHO914?
- Free space is valuable on my desk. So it should be a small device, although with its own screen. So, no USB device like Pico or similar.
- Free space is really valuable on my desk, so the VESA mount to rise the device up with a wall mount gave me a strong purchase decision.
- One can "update" the cheaper Rigol DHO814 to get higher frequencies. I knew that when I made my homework during the purchasing search. But the fact that I do not like devices in white color is more important for me than the price difference to a DHO814. With 830 Euros, the DHO914 scratched the very upper corner of my price range, but... okay.
Of course, I watched nearly every DHO800/900 video on Youtube and read many reviews. The only thing I really disliked with the DHO800/900 was its noisy fan. As I also do some audio recording stuff, my desk environment is very quiet and it should stay as quiet as possible. Thanks to Daves "Rigol DHO800 Fan(boys) Go Wild" video, I recognised that a fan exchange should be generally possible. My inital ideas of a fan replacement were refined with CorelDraw and via DXF export, I then could make a proper fan frame with my CNC machine. Basic material is POM (Polyoxymethylene), very good for purposes like this.
Result: no fan noise at all, nothing. There is plenty of space for the fan to suck air. With you bare hand, you can feel the cooling air coming out of the device grilles on top and bottom. Fantastic.
Disadvantage: if the fan should ever fail, there is no chance to hear that. Maybe, this was the reason why RIGOL took such a noisy fan.

At the end, I built a dust cover to protect the device when not in use.
Enclosed some pictures. Maybe, it is helpful for others. It then would be nice if you reply your thoughts.