Thank you both for the suggestions.
Zorg33, I checked the files and they seemed alright (date, size, everything). I still went ahead and copied the file from C:\AMD just to make sure, still no change I'm afraid. I also uninstalled everything w/DDU, double-checked the files were deleted and installed the driver again. Again, no change.
naska21, could you elaborate a bit? The system is running fine, mining for days non-stop, I just can't make AMD Memory Tweak work for whatever reason. I could be missing something of course.
edit: forgot to mention, no conflicts in device manager.
Oh, I thought you have faced the spontaneous loss of working cards in your rig but if they all are non-stop running then everything is OK with IRQ sharing. Sorry for misunderstanding. As to memory tweaks, I've never known such a situation. Arguably you have quite a bunch of cards attached to motherboard.