I am planning a project for a few Orange Pi Lites as multimedia devices.

I have been testing applications on the Lite with it unenclosed, and without a heatsink and haven't seen any issues with heat so far (running at 1.2 GHz).
 

Is there a general consensus on if this board should have a heatsink when clocked at 1.2 GHz (and is enclosed)?

 

The intended case design has vents. 

2 hours ago, hooby3d said:

The intended case design has vents

 

• small wents don't work with 'passive cooling' AKA 'no fan', same with heatsink fins: if distance between is too small then 'passive cooling' won't work efficient
• if you plan to run longer loads a heatsink is always recommended (ICs waste more energy at higher temperatures) especially on small boards where using the PCB's ground plane as huge bottom heatsink doesn't work that good compared to larger PCB
• the definition of 'issues with heat' seems to be a very personal one (some people are already concernced when a chip exceeds their own temperature and get nervous above 40°C)
• with mainline u-boot we had somewhat wrong thermal calibration so numbers reported by the internal thermal sensor were 10°C-15°C off (reported too low)
• since over a year it's as easy as 'sudo armbianmonitor -r' to get a full monitoring solution for such thermal stuff.

TL;DR: While there's no general consensus on this issue at least those people who dealt with thermal stuff on Allwinner SoCs recommend using always good heatsink (see here or here or here) especially in small enclosures.