if i have rig with first card 8GB and rest 4GB, will it mine ETH after block exceeds 4GB ? if not Phoenix miner, any other miner which will allow to mine ETH with current setup?
Not without huge penality. Just because your first card is 8gb each card has to have its own copy of DAG..so cards with 4gb are already mining slower and will continue to degrade even with zombie mode.
Might consider switching to mining etc as they are reducing dag to 3gb so 4gb cards can mine. But ywa the end of 4gb eth mining is very soon.