Having an issue with one of my 480 cards giving a low hashrate and I notice the memory/core being stuck at 300mHz. Also, when running claymore the computer gets sluggish, something that never used to happen. I've tried uninstalling/re-installing drivers, changing the page file to 16 or 32, plugging in/out monitors, disabling/enabling in device manager, none of which has worked. Some info on my setup:

2 ATI  Radeon RX 480 8GB with modded bios (samsung memory)
ASRock X370 Taichi (AM4) Motherboard
AMD Ryzen 7
Windows 10 64bit
32GB Ram

This used to work fine but I haven't ran claymore on it since version 9.7's release. Updated to 10, same results on both though. Any suggestions or ideas?