I had never noticed that the buffer capacity changes at higher ISOs, but my D3 does it too - at ISO 1600. My older cameras (D2x, D2h, D100) don't do that - the buffer size does not depend on the ISO.
The thing about the buffer size is that you can only fill it in if you keep the continuous drive running. At 3 fps, an 8-frame buffer takes a surprisingly long time to fill. In practice, I pretty much never filled the 10-frame buffer in my 5fps D2x, even though I shoot a lot of sports. (I could, if I tried, of course.)
_____ Brian... a bicoastal Nikonian and Team Member
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