New Build

Keep the hdds away in a nas or something similar.

If that 4Tb are movies or music files without backup that is a bad idea, it is good if you put a 2Tb on your PC and the rest are external drives (it is a good insurance).

Thanks, I have come to the same conclusion, so have ordered the USB3 3.5 Sata docking station (commonly called a "toaster".

That's a good call. The thing is that your mobo will spin up the disks during startup and your ssd will basically sit there waiting for them before your os loads. The toaster removes this bottleneck and takes the noise away (even if it's only a few feet).

Now I'm happy hehehe  

The backup is still (and always) necessary. I suggest putting 'important' things in a certain spot and backing it up periodically.