related to assumptions I made on previous posts, I'm assuming it's not eth, but an ethash coin, right? ETH and ETC won't fit.I've still had it run on a few cards where it doesn't fit using system memory, but at like 2-4MH/s.
the speed on GCN1 and GCN2 cards will go down as DAG size grows, if you're on windows or using the fglrx driver on old linuxes. Radeon HD 7950/7970/R9 280/280X are all GCN1 "Tahiti" cards.
Claymore added a "benchmark" mode for testing how speed will be impacted by different DAG Epochs. (the epochs determine how the size grows)