The ETC (Ethereum Classic) network will perform the Thanos hard fork at block 11,700,000, which will be mined on about November 29, 2020. The mining algorithm of ETC will change from Ethash to Etchash, which means Ethash ASICs and rented Ethash hashpower from NiceHash will not be able to process the new algorithm and mine ETC. Meanwhile, the ETC network’s DAG file will decrease in size. With this decrease, 3GB and 4GB GPUs will be able to continue mining ETC.
After the hard fork, you will need to update your configuration and restart your mining machines.