Two of my 6xMSI R9 390 rigs work fine with stock .rom and Ubuntu 12.04/Cataalyst 15.12. The third one 6xMSI R9 390 with custom rom (made based on https://bitcointalk.org/index.php?topic=1465128) does not work at all on optiminer 1.5(either Ubuntu or Win7. Stops at once after the first card is initiated. Lower intensity does not help) but works fine on Claymore 11.1 and 1.4. 
@optiminer
What can be the reason of that? Can you please give any suggestions how to troubleshoot this?

Thanks