Hi. Just tried again. 5DmkIII, 1080p, 25fps. Constant writing speed ~92MB/sec until exactly 8 minutes and 5 seconds just like the last time. In case of 24fps it`s always 8:25. Then it drops to 0 and starts to very slowly recover. But recording doesn´t end and frames are not being dropped until the card is full. Interesting and weird. Seems like ML bug or Komputerbay 128GB 1000X defect. Global draw was ON this time, but all the features within it were turned OFF.
About the card itself - ML write speed test shows that the card is able to record around ~75MB/sec but in reality I´m gettin much better results. I was able to record 2048 x 1152 24fps in crop mode (Globaldraw OFF, frames forced to 24fps in ML) exactly 7 minutes and 24 seconds and then the speed dropped to 0, just like with 1080p. Constant write speed until then was 94,2 - 96,3MB. This happened twice in a row. So, we may assume that the these record durations are somehow related to the recording format/setup.
I´ll try the Crystalmark a bit later today and let you know.