I have a computer I built in 2012 with a GIGABYTE GA-Z77X-UD3H which rarely fails to boot and must be reset. The error code when it fails to boot is 96, which translates to "Assign PCI device resources".
The video card is an NVidia GTX 750 Ti. I mention that because recently when it wouldn't boot at all, I found a resolution which was to disconnect the video card, flash the bios using onboard video, and then reconnect it. It seems like there is something that still needs to be resolved causing these intermittent issues.
Most of the resolutions I've found while researching it resulted in an RMA. That doesn't seem likely at this point. It's been quite a while since I built and maintained computers so I need some guidance in the next best steps to take to detect any configuration issues that may need to be addressed. I'm concerned I may have overlooked something when I built it.