Odd situation.

Have a rig with 3 x RX570 4GB.  Was getting 27Mh/s with Claymore 10.6.

Had to change rig to different board and hard drive.  Board is the same, hard drive is slightly different (slower, but didn't think this mattered).
Same amount or RAM *GB, same pagefile, 16GB, same divers, same version of windows but now only getting 20Mh/s.

ANy ideas?  Really frustrated.

Drivers version is the latest, 18.2 blockchain from amd site.
Bios is modded the same
"UberMix v3.1

777000000000000022CC1C00AD615C41C0590E152ECC8608006007000B031420FA8900A00300000 010122F3FBA354"

Card info:

Radeon Software Version - 18.2.1
Radeon Software Edition - Adrenalin
Graphics Chipset - Radeon RX 570 Series
Memory Size - 4096 MB
Memory Type - GDDR5
Core Clock - 1244 MHz
Windows Version - Windows 10 (64 bit)
System Memory - 8 GB
CPU Type - Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz

Radeon Settings Version - 2018.0131.1849.33856
Driver Packaging Version - 17.50.17.03-180131a-323782E-RadeonSoftwareAdrenalin
Provider - Advanced Micro Devices, Inc.
2D Driver Version - 8.1.1.1634
Direct3D® Version - 9.14.10.01316
OpenGL® Version - 6.14.10.13506
OpenCL™ Version - 23.20.15017.3010
AMD Audio Driver Version - 10.0.1.6
Vulkan™ Driver Version - 2.0.1
Vulkan™ API Version - 1.0.65

Graphics Card Manufacturer - Powered by AMD
Graphics Chipset - Radeon RX 570 Series
Device ID - 67DF
Vendor ID - 1002
SubSystem ID - 22F7
SubSystem Vendor ID - 1458
Revision ID - EF
Bus Type - PCI Express 3.0
Current Bus Settings - Not Available
BIOS Version - 015.050.002.001
BIOS Part Number - xxx-xxx-xxx
BIOS Date - 2017/05/18 08:21
Memory Size - 4096 MB
Memory Type - GDDR5
Memory Clock - 1750 MHz
Core Clock - 1244 MHz
Total Memory Bandwidth - 224 GByte/s
Memory Bit Rate - 7.00 Gbps
2D Driver File Path - /REGISTRY/MACHINE/SYSTEM/ControlSet001/Control/Class/{4d36e968-e325-11ce-bfc1-08002be10318}/0005

TIA