I am able to manually enable the GPU's, but they show 0 KHs. If I try to use the restart command, they go offline.
How much system memory is needed? I was under the impression that all the mining was on the GPUs and the system ram was just to run the OS. Someone earlier recomended using 8Gb, but I don't understand why that would be needed. The host CPU isn't doing anything but passing packets between the GPUs and the pool or am I wrong?
If you completely remove the --gpu-engine and --gpu-memclock portion do all 4 of them work? Those settings may be a little high for the XFX cards, try leaving them out and if that works, add them back but at a much lower level, like 800. I'm not completely sure about the system memory part, I know scrypt-n uses more memory than just plan scrypt but I haven't had any problems with only 4GB per rig.