How do I accomplish this? I'm trying to take a voltage reading for the IEEE 1394 headers on my motherboard. I'll be using this digital multimeter. To take this reading, should I set it to 20v? Using this as a reference: VIA 1394 brochure It seems as if I should be able to take the positive to the white (volt. +) and the negative to the black (volt. -). I could be totally off, hence my asking here. I know for certain there are electronics wizards here! Another question I'll inevitably be asking is: can I take this reading with the PC powered on? Or is it possible (and maybe safer) to take the reading with the power supply on and the computer powered off. Thanks in advance! EDIT: The reason I'm going about it in this way is because the only Firewire device I have around (that I'm aware of) is an old camcorder that doesn't have current enough drivers.