I don’t remember seeing decay or dwell in the software which is plantcnc usb software that works with buildyoucnc.com hardware. I believe the boards are clones of plantcnc boards in some way. I’ll have to check more on that.
It sounds like you found the spec sheet for these drivers on buildyoucnc.com? I do have heatsinks on the chips that get very warm. Are you saying I need ones on the underside on the pcb as well?
I also have a small desktop fan that points just at the three driver boards but I could add a tiny fan to each board. Guess I’d gave to put one on both sides IF you agreed above that heatsinks on underside are needed.