ACTUAL: 5 kohm pullup on the clock line works just fine.
        10 kohm pullup on the clock line doesn't work any more.


http://electronics.stackexchange.com/questions/33372/spi-bus-termination-considerations

47 pF capacitor after the resistor [just one capacitor even when fanning out]
330 Ω series resistor [one resistor per driver]