IMPORTANT! Ethereum Classic (ETC) network switched to a modified version of ethash, called ETCHash. If you are mining ETC you must upgrade to PhoenixMiner 5.3b or later, otherwise you will get only rejected shares when mining ETC.

The current ETC DAG is 195 instead of 390, with corresponding "shrinking" of the DAG buffer to about 2.5 GB. With this DAG size you will be able to mine with 3GB and 4GB cards without problems. After that, each DAG epoch on the ETC network will be twice as long, so the DAG size will grow with half the speed as before. As a result, it will be possible to mine ETC with 4GB cards for about 4 more years.

The switch went without problems, all our test rigs switched to the new DAG and are mining normally. You may need to run auto-tuning again if to get an optimal speed with the new DAG size.