Appliance hardware, kiosks, industrial computers, etc. Equipment we buy at work, a lot of times it comes with older processors.

Why not virutalize pfsense and that torrent box? An extra 2 computers unplugged.

Youll be fine. Gaming will depend if your ping is high but you cant do a whole lot with that. What Id be most concerned is while gaming, getting bufferbloat due to heavy network use from things such as downloads that will take longer.