olafelch If you use SPI mode, you still need to configure the TMC driver current in Marlin Configuration_adv.h - by default each motor driver is set to 800mA, you should change that according to your motor specifications, and taking into account that you want to use something like 80% of the RMS value of the maximum current for which your motor is rated. To keep things simple, just modify all values to 500-600mA (for each axis where the motor is hot), recompile firmware, reload and also reset and reinit EEPROM. Or you can also just send commands to modify the EEPROM without recompiling the firmware at first, using http://marlinfw.org/docs/gcode/M906.html. Then lower or up the current for each axis until the motors are "just" hot (i.e. you can keep your hand on them). After you find your perfect values that don't cause skipped steps or hot motors, you can modify the firmware to fix the values.