z87 g45 confirmed working with 7 R9 280x cards. z87 g55 and z87 mpower should work fine too.
Rig config :
- windows 8.1
- lbr modified 13.12 amd drivers
- All cards on 1x 16x usb risers.
Burninj, on the z87 g45, did you have to short any of the pins in the PCI-e slots to get all 7 GPUs to work/be recognized?