I have tried openSCAD and FreeCAD, they are both good in their own right, but utimatly they also both have very steep learning curves. I suppose Blender can also be used for CAD but I have no experience with it. I just want to quickly design some parts for 3D printing as a hobby and don’t feel like spending hundreds of hours learning those tools. I am current using Onshape.com, it works well on Linux/Firefox, suits my needs and free to use with some limitations. But it is proprietary :(
I suppose, when you plug the HDD to the computer, it spins up and start drawing more current from the power-supply and the noise disapears. This is because the PSU has a buck-converter, the switching frequency increase proportionally with the current drawn by the load. When the current it almost 0mA, the switching frequency can be audible (electromagnetic forces can make some components vibrate, e.g: coils). When the current is nominal, the frequency will be ultrasound and you won’t hear it. I have observed this with many electronic devices. If you are worried, you can try another power-supply, after checking it has the same voltage and polarity on the plug, and can deliver at least as much current as the original one.
It’s not about Laptop vs worksation. It’s about how new is the Hardware compared to the Linux Kernel shipping with the LTS distribution. If your hardware is older than the kernel, you will most likely not have any problems. For example, let’s say you use Ubuntu 22.04 LTS, which ships with Kernel 5.17 releaed in may 2022, if your computer is made of parts released in 2021, no problem.
You say the sound comes from the power supply and the HDD is not plugged into the computer. My diagnistic: the power-supply makes a noise when it operates at very low load (almost 0mA of current), it is probaly making the cyclic noise because of some blinking LED or another very small variation of the loaf somewhere. This is a very common symptom of cheap power-supplies, but it doesn’t necessarly mean it isn’t working normally, just an annoyance.
When I opened the package, I was sure I was missing one of the chair’s leg. I went back to the shop and they told me everything is there. So, back home I started to assemble it, now I am finished and I am left with an extra chair leg. What do I do ?