Flash will run on 4x, but at the time I ran that test there were no 4-card quants for the full 744B-A40B 5.3 model. There are now, though, with KLD figures close to the FP8 level. I need to do some more benchmarking to see if they live up to the hype.
It actually runs fine at FP8 on this hardware too, with the full 1M context.