[rvense]

Even old laptops can make good servers. Built-in UPS and screen for recovery. Depending on just how old, you might even be able to add more storage using USB3 ports, or with a controller in an ExpressCard slot or in place of the wireless card, or by replacing an optical drive.

[zeppelin101]

This! I have a highly underpowered laptop (which I bought brand new but at a very low cost for travel purposes) that I just didn't know what to do, because it was so damn annoying and awkward for any personal use. The keyboard was quite awkward. The trackpad was even worse. The display was so basic that even I didn't want to use it for YouTube/Netflix. The CPU... well you get the point. Finally, just a few weeks ago, I thought that I would really like to build a Linux server and thought of my Raspberry Pi 3. I remembered that I would need to connect an external HDD to make it even halfway useful for data storage. I would also need to find a USB wifi adapter (because my home setup currently isn't wired). Then I looked at this laptop which had been collecting dust for like 2 years. I realized it was perfect for my needs: has a 1 TBB HDD (not SSD) and a built-in wifi adapter. I installed Lubuntu (one of the least resource intensive distros) and then started installing numerous services on it: Nextcloud, IRC bouncer, SMB server. I only have Nextcloud running at the moment as it's the only thing I've been able to make serious use out of, but it just works.. perfectly.