Check if any windows updates got installed on the date that your problems began
If it has been working for months without any problems, and you have not made any changes, then it could be a hardware fault.
I would first check that the power cables into the risers have not started to burn out (I've had a few do this).
The next thing would be the usual, test each card individually, then add the cards back one-at-a-time.
After yet another restart, the problems were resolved. No windows updates either.
Just in case you guys can find anything: Those are the log files when it crashed:
19:25:42:102 11d4 Check and remove old log files...
19:25:42:116 11d4 args: -epool *deleted by me* -ewal *deleted by me* -epsw x -esm 0 -estale 0 -mode 0 -asm 1 -dcri 20 -cclock 1125 -mvddc 900 -cvddc 900 -mclock 2200,2150,2150,2100,2200,2125 -dcoin lbc -dpool *deleted by me* -dwal *deleted by me* -dpsw *deleted by me* -allpools 1 -ethi 12
19:25:42:116 11d4
19:25:42:117 11d4 ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»
19:25:42:117 11d4 º Claymore's Dual ETH + DCR/SC/LBC/PASC GPU Miner v10.1 º
19:25:42:118 11d4 ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ
19:25:42:118 11d4
19:25:42:320 11d4 ETH: 1 pool is specified
19:25:42:321 11d4 Main Ethereum pool is *deleted by me*
19:25:42:321 11d4 LBC: 1 pool is specified
19:25:42:322 11d4 Main LBRY pool is *deleted by me*
19:25:43:362 11d4 OpenCL platform: Intel(R) OpenCL
19:25:43:362 11d4 OpenCL platform: AMD Accelerated Parallel Processing
19:25:43:365 11d4 OpenCL initializing...
19:25:43:365 11d4 AMD Cards available: 6
19:25:43:366 11d4 GPU #0: Ellesmere, 8192 MB available, 36 compute units
19:25:43:367 11d4 GPU #0 recognized as Radeon RX 480/580
19:25:43:367 11d4 GPU #1: Ellesmere, 8192 MB available, 36 compute units
19:25:43:368 11d4 GPU #1 recognized as Radeon RX 480/580
19:25:43:368 11d4 GPU #2: Ellesmere, 8192 MB available, 36 compute units
19:25:43:369 11d4 GPU #2 recognized as Radeon RX 480/580
19:25:43:369 11d4 GPU #3: Ellesmere, 8192 MB available, 36 compute units
19:25:43:370 11d4 GPU #3 recognized as Radeon RX 480/580
19:25:43:370 11d4 GPU #4: Ellesmere, 8192 MB available, 36 compute units
19:25:43:371 11d4 GPU #4 recognized as Radeon RX 480/580
19:25:43:373 11d4 GPU #5: Ellesmere, 8192 MB available, 36 compute units
19:25:43:374 11d4 GPU #5 recognized as Radeon RX 480/580
19:25:43:374 11d4 POOL/SOLO version
19:25:43:375 11d4 b421
19:25:43:375 11d4 Platform: Windows
19:25:43:414 11d4 start building OpenCL program for GPU 0...
19:25:43:967 11d4 done
19:25:44:171 11d4 start building OpenCL program for GPU 1...
19:25:44:554 11d4 done
19:25:44:757 11d4 start building OpenCL program for GPU 2...
19:25:45:123 11d4 done
19:25:45:325 11d4 start building OpenCL program for GPU 3...
19:25:45:684 11d4 done
19:25:45:886 11d4 start building OpenCL program for GPU 4...
19:25:46:229 11d4 done
19:25:46:431 11d4 start building OpenCL program for GPU 5...
19:25:46:773 11d4 done
19:25:46:997 11d4 GPU #0: algorithm ASM
19:25:47:020 11d4 GPU #1: algorithm ASM
19:25:47:051 11d4 GPU #2: algorithm ASM
19:25:47:079 11d4 GPU #3: algorithm ASM
19:25:47:107 11d4 GPU #4: algorithm ASM
19:25:47:140 11d4 GPU #5: algorithm ASM
19:25:47:141 11d4 cudaGetDeviceCount failed (35, CUDA driver version is insufficient for CUDA runtime version), probably no CUDA devices
19:25:47:142 11d4 No NVIDIA CUDA GPUs detected.
19:25:47:142 11d4 Total cards: 6
19:25:47:571 11d4 No NVIDIA cards in the list, NVML library will not be used.
19:25:47:586 1114 Cannot resolve '*deleted by me*'
19:25:47:588 1114 ETH: Stratum - Cannot connect to *deleted by me*
19:25:47:588 1114 ETH: Stratum - Failed to connect, retry in 20 sec...
19:25:47:677 11d4 DUAL MINING MODE ENABLED: ETHEREUM+LBRY
19:25:47:678 11d4 ETH: eth-proxy stratum mode
19:25:47:678 11d4 "-allpools" option is set, default pools can be used for devfee, check "Readme" file for details.
19:25:47:678 11d4 Watchdog enabled
19:25:47:679 11d4 Remote management (READ-ONLY MODE) is enabled on port 3333
19:25:47:679 11d4
19:25:47:716 6a0 LBC: Stratum - connecting to *deleted by me*
19:25:47:786 6a0 send: {"id": 1, "method": "mining.subscribe", "params": ["dual 1.0"]}
19:25:47:786 6a0 send: {"id": 5, "method": "mining.extranonce.subscribe", "params": []}
19:25:47:786 6a0 send: {"id": 2, "method": "mining.authorize", "params": [*deleted by me*}
19:25:47:786 6a0 LBC: Stratum - Connected (*deleted by me*)
19:25:47:828 6a0 got 162 bytes
19:25:47:828 6a0 buf: {"id":1,"result" *deleted by me*" ,"error":null}
19:25:47:829 6a0 parse packet: 161
19:25:47:829 6a0 new buf size: 0
19:25:47:881 6a0 got 514 bytes
19:25:47:881 6a0 buf: {"id":null,"method":"mining.set_difficulty","params":[256]}
{"id":null,"method":"mining.notify","params": *deleted by me*
19:25:47:881 6a0 parse packet: 59
19:25:47:881 6a0 remove first packet 454
19:25:47:882 6a0 new buf size: 454
19:25:47:882 6a0 parse packet: 453
19:25:47:882 6a0 new buf size: 0
19:25:47:955 6a0 got 36 bytes
19:25:47:955 6a0 buf: {"id":2,"result":true,"error":null}
19:25:47:955 6a0 parse packet: 35
19:25:47:955 6a0 LBC: Authorized
19:25:47:956 6a0 new buf size: 0