I’m still playing around with optimal CUDA box configurations, and have decided that I want all my CUDA cards to have a free spot below them so the intake fan can pull air in better. As such, some nice looking motherboards like the MSI NF980-G65 won’t work, because even in the 2 card mode, it has them in spots 1 and 3, so the first card has no breathing room. You can use 1 and 5, but that reduces the card in 5 to 8x (which may or may not matter.)
I recently found the older Asus M4A79T mobo, reasonably priced at $139 from NewEgg, and gave it a look over. According to the manual, you can configure the PCIe bandwidth in the BIOS, giving you the option to control whether the pairs of slots are x16/x1 or x8/x8. Additionally, one could put in a PCI video card in the 4th slot, leaving plenty of air space for the x16 spots at 1 and 5. This flexability looks useful, and with nothing out there for AMD with 3 spaced out slots, (except the DFI Lan Party mobo, which has TERRIBLE support reviews,) this looks like a nice option for a 2 card x16 mobo.
Does anyone have any experience with the Asus M4A79T mobo for Cuda calcs? And how do you all prioritize card airflow vs. the usefulness of onboard video?