you havn't enough system memory. try it with 2 gpu and your config will work... so with 4 gpu you should rise your system memory or try it with -R 1280 buffer-size 1295, but these results will not satisfy you.
good luck
If you don't understand how something work don't fool people lol! Ram have nothing to do with the card after the start of the miner because it is used once just to carry the data to the card. The actual problem with the dead/sick gpu's is caused by the vram clock.
BTW 8 gb ram is enough for 6 gpu's and even with 4 gb you can run 6 gpu's no matter what os you got.