Have you verified power usage when running in single mode? I've got 6 of these in an enclosure running CPUminer to mine and they all went into an over heat/shut down while mining LTC ONLY. Thats kinda lame. The other three are out on a workbench and they seem to be OK. Only three of them have reached over 300khs and this is clocked at 800 mghz.
I'm sure the controller is the "missing link" here but I'd really like it if they worked better without a controller.
Oh well, price one pays for getting in on new tech.
You might want to disassemble the overheating units to verify that the thermal pad is making contact with the chips. Someone reported that the fan wires managed to get wedged between the chip and pad. The other thing to keep in mind is that the units won't be necessarily stable at 800 MHz.
I've made it a habit to take EVERYTHING I get for mining apart to inspect it before I power it up. All the Avalons I bought had loose screws, all the Antminers I bought had loose screws and even these Gridseeds had loose screws. I did make sure that fan wires were not pinched and that the thermal pads all look like they are where they should be. Only one of them was obviously out of place and I found that before I powered it up.
My problem with not running these at 800 MHz is that this is the ONLY way I've been able to get a few of them to reach above 300khs's. One of them is sitting at under 100 right now.
Piss poor....
I'm curious to know if people with controllers are getting different results.
We are getting a new update for the controllers that should solve most of these issues. Will let you know!