Morning Jonathan..!

Tried all kernal speeds from 25KHz to 60Khz, makes no difference...

Seems my PC is a dual processor, 2 x 3GHz P4... Have it set for standard PC and have done all the optimizations recommended for Mach3.. Really is a bare bones machine and runs very fast, boots in 11 secs... Even running complex code the processors never get to more than 4% usage... Everything disabled that is of no use, using a pci graphics card (not onboard one which seems to be an issue on some machines)..
Re-checked all my cables and drivers/board (which are very cool due to a pair of fans mounted above them)..
Just swapped round a motor (had 2 spare 3Nm) and made no difference..

Am at a loss now.. No hair left to pull out and no idea what to try next...

Steve..