Hi,
I’m running a fairly modest system (8 extensions, though most with H.264 video capability) using a Foxconn Nettop NT-3500 unit. I had a 4GB SoDIMM and a spare SSD lying around, so have dropped those in.
For something so cheap, the specs are not too shabby and you get a 1.6 GHz dual-core AMD CPU included. Performance to date has been absolutely fine. My system fully boots from cold, with Asterisk and FPBX running in around 50 seconds.
My ‘hardware redundancy’ solution is another NT-3500 sitting on the shelf!