Here's my post from the thread where we got OT and started talking about CF card speed:
This question of CF speed and 7xx boxes seems to keep coming up. As I said above, I have never had a problem with CF speed on either a 702 or a 788T. That said, I have not tried every available CF card. But here is the data on the cards I do have, listed in order from slowest to fastest:
Card size "speed" 788T speed test results
Kingston Elite Pro 32GB 133x 4.8 MB/sec
AData Speedy 16GB unknown 6.4 MB/sec
AData Speedy 4GB unknown 7.2 MB/sec
SanDisk Ultra II 2GB unknown 7.8 MB/sec
SanDisk Extreme III 16GB unknown 14.0 MB/sec
Recording 24 bits at 96000 samples/sec is (from the SD 788T v1.65 manual, page 101):
(24 x 96000) / (1048576 x 8bits) = 0.275 MB/sec/track (rounded)
Recording 8 tracks of 24/96k results in a data rate of 0.275 MB/sec/track x 8 tracks = 2.2 MB/sec
As you can see, the slowest card listed above (4.8 MB/sec) should be fast enough. As a test, I used the "slow" Kingston Elite Pro 32GB card to record about 3.5 hours of 8 track 24/96 without any CF failures or warnings. After inspecting and listening to the sound file, I could not find any errors. The card was newly formated and so not fragmented. If the card had been highly fragmented, maybe my results would have been different.
Now I do not own nor did I test a SanDisk Extreme III 32GB card, but I suspect it is not much slower than the 14MB/sec 16GB card I did test. In other words, the SanDisk Extreme III 32GB card should work fine for 8 tracks of 24/96k, IMHO.
I have noted that my 788T will write faster to the same CF card than will my 702. However, both recorders can write fast enough to any CF card I own to be able to record at the recorder's highest data rate (i.e. 8 x (24/96) for the 788T or 2 x (24/192) for the 702).