jase wrote:I'm starting to think my problem is something to do with power. This drive seems to be drawing a LOT of current according to my multimeter :/
Out of curiousity, how much current on each rail?
jase wrote:Is it safe to run a second PSU in parallel with the one in the case? Or would the floating ground supplies interfere with each other?
What do you mean by parallel? If you mean hooking the outputs of both supplies to the same bus, then the answer is no. Only specially designed power supply systems can safely do that. If you mean use one power supply to power the motherboard, for example, and another to power the drives, then yes it can be done. Make sure to tie the black common leads from the two supplies together at one point so that they share a common voltage reference if they aren't already tied to earth ground. And make sure each supply is sufficiently loaded. Switching power supplies often require a minimum load in order to properly regulate the output voltages. Also, make sure there aren't any hidden back-door paths (e.g. +5 V lines on signal connectors) that would connect the power rails of the two supplies together. Finally, be aware that your chances of running into electrical interference/noise issues running two power supplies is probably increased. Returning current may have to take circuitous routes to complete the circuit, leading to large loop areas and their inherent susceptibility to generating and receiving electrical noise.
I really think you would be better off upgrading to a beefier power supply if you are running low on power. I seem to recall you recently posting that you have a 200 W power supply in your system. That is small if you have a lot of peripherals hooked up, and you can easily replace it with a 350-400 W supply.