It's looking more certain that what we've been seeing in our DC is a poor reaction of SP30s to temperatures below about 6°C. We haven't seen any issues with SP10s yet at these temperatures.
Some machines work fine at low temperatures. I've seen a few operate just dandy at intake temperatures as low as 2°C. However, others will show problems at intake temperatures as high as 8°C.
When a machine has trouble at low temperatures, it's often specific ASICs that show the problem (often #2 and #17). It's not always the ASICs in the front that have issues, though it seems more common to be those. Once an ASIC has trouble at low temperatures, it sometimes has trouble even when warmed up. Sometimes it has to be disabled permanently; other times it can be enabled once the machine is warmer.
Indeed, but a hardware to be reliable, must handle 25°C variation without too much trouble.Here at low temperature some ASICs can't start. It will be a good idea to add a 'delay' option for the troublesome ASICs where they are turn off during the cold start and enabled later. Adding an option to change the Fan speed according to the intake temperature, will be a good too idea too. (I suspect this issue to trigger some machines crashes when minergate restart).