I can record 1920x1080 24p stable at about 89mb/s on a KB 64GB 1000x on the 5D3 (Oct 25 build). Keeping the 89mb/s in mind, I changed settings to 60p in the Canon menu and adjusted the resolution so it was set to about 82mb/s. The recording stopped and stated it was a bug and to report it. So, here I am... Some more details, I had Highlight Tone off, NR off, lens corrections off, Auto Lighting Optimizer off, HDR off, only had the histogram and zebras on, small hacks on, card warm-up 1GB. It was not until I dropped the resolution to about 59 mb/s that I could get continuous recording at 60p. I also noticed when I went back to the stable 1920x1080 24p, the 89mb/s was no longer green and went back to green when I dropped the resolution to record at 59mb/s. I did however, get to record continuously at 1920x1080 24p. Known issue? Need more info?
Issue #1734 duplicate