Not my favorite PSU format, and as you say, the location of it, and the system on the floor = vacuum cleaner.This is one of my DELL Precision 650 workstations. A few of my DELL PowerEdges have like this too. It's bad and you can trust me you don't want it. It's OK when new or if you keep it on a desktop but otherwise no thank you!
Clean layout of the internals though.
Were you ever able to mitigate it with anything such as different feet or a foam sheet that's available?Also with a PSU in the bottom most systems seem to telescope more noise into whatever surface it's sitting on. If that's a thin-skinned desk then the desk will act a bit like a loud-speaker and amplify the noise.