my mine drops down to 410-415GH. I would rather keep it running and pay a deposit so he would ship a new controller out and refund me after he receives the bad one than shut the miner down for a week or two.
It may not be a controller issues as from your description.
Are you seeing any "x" or "-" in you asic status page?
Give me your Ant S3-es fans speed, temperatures of miner and ambient temperature?.
Most probably its, the heat dissipation issue and the chip are throttling to lower clocks automatically as in GPUs.
As already advised by bitmaintech support engineers, unscrew the chip side heatsink and check the condition of thermal grease.
Remove it with a cloth and apply new thermal paste grease and it will be mining back at 441.
Use a good thermal grease which provide conductivity above 3.
sorry but I can not access my interface for this miner. It's still mining and Bitmain PM that he has turned my problem over to his engineer which I am waiting to hear from. I have not tried to reboot or use the reset button yet as I am afraid the miner may not start back up. But once I get thru that problem I will give what you suggested a try. But the last time I was able to get on the miners interface ( a couple days ago) I was seeing no x's and it all looked fine. Just starting out normal speed and slowing dropping down. Thanks