What you guys seeing for HW errors I'm, seeing about 60 and 70 on boards 1 and 3 after 24 hrs. Boards and 2 and 4 only have a few HW errors.
Mine has been running about 19 hours at an air conditioned data center. Chain 1 has 40 hardware errors, chain 2 has 1 error, and the rest have zero.
This seems to be a trend in recent Bitmain hardware. One of my S9's (the most recently purchased one) also has one board that gets 10x hardware errors of the other boards. I tried down clocking that unit to reduce the hardware errors.
Back on the L3+, I don't think that temperature is a factor. One of the hottest boards has zero hardware errors.
On the hardware issues what I have seen with the L3's is that if a board throws errors as long as it isn't a high error rate the board is OK. However what I have seen is that boards in this state can become more unstable over time and as ambient temps rise. Some of those boards will begin escalating errors until the miner starts to crash.
So temps are a factor with the boards and HW errors, however temps are usually not the reason the board has the errors to begin with. The recommendation by many is to disable the auto fan and run the fans as a percentage such as 70-80% to ensure the inside boards most affected by heat are getting more air flow.
Like you stated this is pretty standard on the Bitmain miners to some boards with some errors. It isn't a problem unless those errors begin escalating. This is the dance I have been doing since we started this thread here on the forum with the L3 and the hardware issues. Hopefully turning up the fans will help some people. For those in a climate controlled facility this may not be as big a factor.
Keep an eye on your L3's is the best advice I can give aside from turning up those fans.