VBR -16 and CBR 3.0x

[aliwalker]

Canon 5D Mk2 1.4 50mm ML 2.3 installed. Pic Profile Technicolor, 600x CF card

QUESTION
- I can only get 50mb/s on either of these settings and can't get my CF card to overload. I noticed on vimeo someone managed 120 odd mb/s with a x1000 card. Is there a setting that prevents over-buffering which I have turned on? In  both situations there is the data rate is constant. (monitoring using Quicktime Pro)

I would of thought the CBR setting would give a constant bit rate despite what is filmed, and VBR fluctuates depending upon the scene?

Totally loving the 2.3 update btw!

[scrax]

CBR is more constant than VBR but it's also influenced by the scene and also from ISO settings lower ISO higher bitrate possible