I used to run my old laptop from ~2008 with intel P8600 CPU, 4GB RAM and two cheapest kingston 120GB SSDs in RAID0 for postgresql dev work. Main reason was that I didn't want to bog my main desktop when re-ingesting large data sets and then indexing or updating it. Worked very well even though it had SATA II, guess random I/O on SSD is no issue even for older hardware. Needless to say it beat my main desktops uptime because of having battery working as a great UPS. And it could always display htop/iotop on it's display as a nice indication that something was being worked on. Reusing old hardware is cool.