Fanless case watch your temps and apply new paste
I've got an i5-based Qotom Q355G4. It's been chugging along nicely for the past three years. Two days ago, though, it started acting sluggishly. Logging in via the web interface was painfully slow, and it would hang. During the few chances I got to see the status page the temp section was through the roof.
Figuring I had nothing to lose if it was dead, I cracked open the case to check the thermal paste. I removed the heatsink from the CPU, cleaned off all the old paste with alcohol and applied new, and it was back in business. Temps were considerably lower, but it'd still hang. I suspected it might have been the mSATA SSD, so I did a fresh install, erasing the existing contents of the SSD. Now 12 hours later the machine is humming along again without issue.
I do plan on replacing the SSD, but meanwhile we're back online.
Now, dealing with Verizon for FIOS support... ugh, that's a new level of torture. It took hours of waiting for a call back (est time was quoted as 1 hour... it was 3). Then it was an entry support rep that I humored through the whole rebooting the router dance. After 40 minutes, though, I insisted it be escalated to someone that actually understood what "tell the ONT to release the DHCP address" means. This to get a standby piece of equipment working while I wrangled with fixing the Q355G4. Another two hours, dropped calls, call backs with no one on the line... eventually it worked. Then I got the Qotom fixed and, thankfully, it also got a proper WAN IP address. FIOS service is great... until you have to deal with their "support" personnel.
Anyway, long story short, check the thermal paste on your CPU. Fanless or otherwise, the paste does dry out over the years and applying a fresh dab is probably something that should be a part of a maintenance cycle.
When I had and used an SG-2220 (I know, completely different animal) I bought a dual USB-powered fan system.
This kit, one fan below, one fan above, kept the system at a cool 75F on the fans lowest speed setting. Worked great, in my opinion.
@akuma1x I have also used AC Infinity external USB fans. First for a game console and then another for this fanless Qotom box. It did help, but replacing the paste helped MUCH MORE.
I have another fanless machine and plan on doing the paste for it later this week.