Typically when they do, they're built in to server chassis as a remote management/LOM tool. A few such add-on cards have been made over the years, though -- th

Typically when they do, they're built in to server chassis as a remote management/LOM tool. A few such add-on cards have been made over the years, though -- the PC Weasel 2000 was quite a nice card back in the day: https://web.archive.org/web/20110406024209/http://www.realweasel.com/intro.html https://web.archive.org/web/20110406024209/http://www.realwe... Others like the Enidan J1 were specifically targeted toward people building clusters out of commodity hardware: https://web.archive.org/web/20010511215150/http://www.enidan.com/j1/summary.html https://web.archive.org/web/20010511215150/http://www.enidan...