I have a mid 2010 5,1 2x2.4 Quad Xeon, 12 GB with one spare harddisk bay and one spare optical bay. I've got a flashed MSI R9 280X Gaming 3G, currently powered via PCI slot plus the two six-pin PCI boost cables, one with a 6-8 converter on it. In operation it appears that one of the two PCI boost connectors provides about half of the power draw required - when running FurMark in a window at 1024x680 with no anti-aliasing the card is drawing about 2.5amps from PCI slot 1, 3amps from PCI Boost B, and about 6amps from PCI Boost A. However when subject to high graphics processing loads (e.g. FurMark at significantly higher resolutions and / or anti-aliasing) the card draws too much current / overloads something and trips the Mac Pro. One possible solution would be to combine the current two PCI Boost cables into a single connection (using a 2-1 cable) and use this to feed the high-current socket, and to get a supply to feed the other socket from elsewhere in the 5,1. So my question is would the power connections to either the spare HardDisk or Optical bay be strong enough to provide the second PCI boost power requirement? I'm the lower-current power PCI boost input to the card will need up to about 5amps. Does anyone know whether either connection can provide this?