I assume that you mean that you changed the power supply cable and not the power supply itself. Did you also check the ribbon cable between the mainboard and the front panel? I've heard that this can sometimes be as problematic as the ribbon cable between the power supply and mainboard. I would suggest checking the voltages on the power supply connector with the drives connected and the DTivo powered up. You should get approx. +5 volts and +12 volts on the red and yellow pins with respect to ground (black wires). Make sure your drives and fan are spinning up when power is applied. If not, then the power supply is probably the culprit. The fact that the drives work in another DTivo tends to rule them out as being bad. Also check and make sure the IDE cable is seated properly at each end.
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