Your farm is out of memory most likely. Reduce -I to 15.
why all the miners are not working in solo mode minus the 3.7.8 version of cgminer? i find this utterly stupid
Because no one cares to fix solo mining in SGminer. I don't maintain it.
Thanks ghostlander!, Problem fixed. Finally I get 1.9Mh/s with 4 R9 280x.