Miner shows the following error if more than 1 card are installed
>sgminer.exe -n
[15:47:55] CL Platform vendor: Advanced Micro Devices, Inc.
[15:47:55] CL Platform name: AMD Accelerated Parallel Processing
[15:47:55] CL Platform version: OpenCL 2.0 AMD-APP (2348.3)
[15:47:55] Platform devices: 7
[15:47:55] 0 Ellesmere
[15:47:55] 1 Ellesmere
[15:47:55] 2 Ellesmere
[15:47:55] 3 Ellesmere
[15:47:55] 4 Ellesmere
[15:47:55] 5 Ellesmere
[15:47:55] 6 Ellesmere
[15:47:55] ATI ADL Overdrive5 API found.
[15:47:55] ATI ADL Overdrive6 API found.
[15:47:55] Found 42 logical ADL adapters
[15:47:55] GPU 0 assigned: iAdapterIndex:0 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_4&25A57E32&0&00E0A iBusNumber:2 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 1 assigned: iAdapterIndex:6 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_4&2DDC6CBB&0&00E1A iBusNumber:3 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 2 assigned: iAdapterIndex:12 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_4&36135B44&0&00E2A iBusNumber:4 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 3 assigned: iAdapterIndex:18 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_4&63638AD&0&0008A iBusNumber:1 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 4 assigned: iAdapterIndex:24 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_4&6AE6995&0&00E4A iBusNumber:10 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 5 assigned: iAdapterIndex:30 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_6&1CCB9A36&0&001800E3A iBusNumber:9 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 6 assigned: iAdapterIndex:36 iPresent:1 strUDID:PCI_VEN_1002&DEV_67DF&SUBSYS_E347174B&REV_C7_6&2D3EE07A&0&000800E3A iBusNumber:7 iDeviceNumber:0 iFunctionNumber:0 iVendorID:1002 name:Radeon (TM) RX 480 Graphics
[15:47:55] GPU 0 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:55] ADL GPU 0 is Adapter index 0 and maps to adapter id -1132213824
[15:47:55] GPU 0 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:55] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:55] GPU 1 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:55] ADL GPU 1 is Adapter index 6 and maps to adapter id -1130381248
[15:47:55] GPU 1 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:55] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:55] GPU 2 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:55] ADL GPU 2 is Adapter index 12 and maps to adapter id -1059653248
[15:47:56] GPU 2 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:56] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:56] GPU 3 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:56] ADL GPU 3 is Adapter index 18 and maps to adapter id -1256926016
[15:47:56] GPU 3 BIOS partno.: 113-2E3470U.X51, version: 015.050.000.000, date: 2016/08/02 04:40
[15:47:56] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:56] GPU 4 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:56] ADL GPU 4 is Adapter index 24 and maps to adapter id -950863680
[15:47:56] GPU 4 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:56] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:56] GPU 5 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:56] ADL GPU 5 is Adapter index 30 and maps to adapter id -987134336
[15:47:56] GPU 5 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:56] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:56] GPU 6 Radeon (TM) RX 480 Graphics hardware monitoring enabled
[15:47:56] ADL GPU 6 is Adapter index 36 and maps to adapter id -1023380032
[15:47:56] GPU 6 BIOS partno.: 113-2E3470U.X5W, version: 015.050.000.000, date: 2016/09/21 02:29
[15:47:56] Failed to ADL_Overdrive5_ODPerformanceLevels_Get
[15:47:56] 7 GPU devices max detected
Drivers 17.5.2 (before 16.9.2). Another rig with the same setup works fine (asrock btc pro + rx480).
Claymore (eth) works without problems.