My primary server uses to be a 12 year old laptop with an SSD. I deployed a laptop server in rural Greece and its bulletproof, it VPNs back home to the US and works during short power outtages. Only caveat is the CPU fan, if you run the server with a high load the fans are not designed for years of high usage. I got crazy enough with one server where I cut the bottom out and mounted a large aluminum plate to the CPU heatsink and made it passively cooled.