the machine is running for 10-15 minutes sometime 30-40 minutes with perfect hashrate and perfect temp and then suddenly it stops and starts within second and then the machine is not able to mine it is running miner fan is running at faster speed then slower speed again the same and not mining
well it could be the fans are damaged not the controller. and once again it really is not your fault since they do not say anywhere don't set the fans on manual speed of 100%
But there is no question that you need to replace
1) the fans and the controller----- worse case
2) the controller
3) the fans------------------------- best case
try a simple test set freq to 500 fans to 80%
see if it runs longer like for hours and hours.
if it keeps running at 80% fans and freq of 500 .
you could stay at that point or you could order rma on fans and controller.
my guess is lower freq and lower fans won't help.
my guess is you only need the controller.
of course you will need contact bitmaintech in china vs bitmainwarranty in usa.
my opinion is they should have warned about 100% manual fan speed setting. they did not.
i warned about 100% manual fan speed settings but I am just a miner.