Yours should work until EPOCH 379, maybe 380, however 381 will definately not work. If you are getting issues now then you are most likely not using onboard graphics as the main GPU in Linux. Basically go to your motherboard bios and enable onboard graphics, they will usually be automatically disabled and plug your monitor into the motherboards DVI connector and disconnect from the GPU.

Then try again and it should work. You can also use the -benchmark setting and try different DAG numbers and you will know exactly when it will stop to work for you. You pretty much got a month or so to go. After that you need to either upgrade the GPUs or use another software like lolminer which can mine after 4GB at reduced speeds.