My PC was freezing when I rendering my project, must reset with the power button. It renders fine when I use quick setting, it was only append when I use middle setting. I use Maxon Cinema render. Before the freezing, the software will use all my 16G memory. My CPU is i7 8700k and GPU is GTX 1080 8G. I also use Cinema 4D, and it’s fine. I think my PC is able to do rendering with middle setting.
If you leave it for a little bit after it initially freezes, if the render was already nearing completion, it might finish as it dumps into virtual memory, else it is most likely what you have pointed out, the shortage of RAM.
Windows will generally allow programs to use virtual memory up to an amount equalling your RAM. When it does so your computer may grind to a halt if no RAM is reservered for other purposes as virtual memory is dependant on your harddrive speed which is orders of magnitude slower than RAM.