1) Ron's numbers are wrong, sadly, check my proof video I posted in this thread. I have used the fastest memory card available, Lexar 128GB CF UDMA7 Pro, which I use daily with my 5D3. The 5D3 Canon also claim to be able to fully utilize any UDMA7 card with up to 167MB/s, which I have found to be wrong.
The 5D3 is capable of almost 100MB/s, about the same as the D4. (tested with speeds which allowed for continous shooting without the buffer stopping)
2) I am capable of shooting 33-34 RAW images at 6fps on my 5D3 with the Lexar UDMA7 card before buffer stops.
3) Seem like I am not entirely correct on the D4, (although I have read several places it could go higher), this guy is achieving 6-7 seconds continous shooting until buffer is full (at 05:45), this should mean 60-70 RAW files:
XQD + Nikon D4 full speed test
I have also done extensive speed testing on my own with the 5D3, 5D2, the D4, D800 and D800E, all with the Lexar 128GB UDMA7 CF Pro 1000x, since I work a lot with stop motion video in the dark, and need the cameras to be able to shoot as fast as possible without the buffer stopping. The 5D3 has about the same write speed as the D4. IMO the D4 is actually slightly disappointing in its computing power, taking into account its fast shutter mechanics. Still its buffer seem to be larger than the 1DX, since RAW files of D4 is actually 33MB compared to 28 on the 1DX.
With the price tag, and the shutter speed and the computing power availbale on the 1DX, I have to say I it is disappointing Canon did not implement a bigger buffer, given also how cheap flash ram is these days, even if it might be enough for many people.
For my type of work, I am guessing the 1DX will still outperform the D4 (shooting as fast as possible without the buffer interfering), but thats not the only point. Even if my type of work is not what most people do, I also do regular work, such as wildlife and bird photography (BIF), and what If I am shooting an eagle diving down for a fish? This is a moment which could take much more than 3 seconds, sometimes 7-8seconds. But then the buffer on the 1DX is full..
And if I have to turn down the shooting speed of the 1DX to not fill up the buffer, then what is the point of me spending 7000 dollars on the 1DX rather than just using my 5D3 ?
See, now you're going to make me go and buy a Lexar 1000x to get that 33-34 RAW on my 5D3.
I'm assuming the 1Dx you had was a pre-production unit, so perhaps it's still got a firmware update to go before it's at full speed. (Maybe).
It's also kind of weird that the D4 being 16Mpix has a larger RAW file than an 18Mpix 1Dx or a 22Mpix 5D3?
And I totally agree with you on the fact that RAM is cheap....it would be next to nothing to implement a RAW buffer of 60 to 96 RAW images for a 5-8 second burst buffer.
Here is some more info on a few scenarios:
"The Lexar 1000x honestly didn't really do any better than a Sandisk Extreme Pro 90MB/s card with a 5D2 or 7D (or surely xxD) cam but with the 5D3.... WOW. And it lets the 5D3 deliver best in class buffer and longer contrinuous shooting times than either the 5D2 or 7D.
A few numbers (all tests at 1/800th shutter, no IS, no AF, no NR or any other in cam jpg special processing options, max continuous drive mode selected (7D pointed at a bright light so as to maintain max frame rate)) with the raw number being number of shots before you hear it slow down shooting and timed number is the continuous time you could shoot non-stop at the camera's max frame rate (derived by a simple frames/max fps of camera):
Test 1 (lens cap on or super underexposed near black frames (i.e. with requiring minimum for storage) at ISO100 on 5D3):
14 shots with a slow Lexar 16GB 200x card
17 shots with a 30MB/s SanDisk Extreme III 8GB card
20 shots (3.3s) with a 32GB SanDisk Extreme Pro 90GB/s card
35 shots (5.8s) with a 32GB Lexar 1000x card (whoa! 35! vs 20! 5.8s of continuous shooting vs only 3.3s!)
(so the Lexar 1000x makes a surprisingly large difference on the 5D3 and is well worth the $ if you seriously shoot action with the 5D3, do note that the 16GB 1000x card is said to be slower than the 32GB and larger 1000x cards so the advantage may be less if you go for the 16GB size; with this speed card the 5D3 continuous shooting time easily beats the 5D2 and 7D)
Test 2 (as above but on a 5D2):
16 shots (4.1s) with a SanDisk Extreme Pro 90MB/s card
17 shots (4.3s) with a Lexar 32GB 1000x card
(so the extra $ for the Lexar 1000x makes no difference on a 5D2; with this speed card the 5D3 actually lets you shoot continuously for less long than the 5D2 or 7D)
Test 3 (as above but on a 7D):
29 shots (3.7s) with a SanDisk Extreme Pro 90MB/s card
28 shots (3.5s) with a Lexar 32GB 1000x card
(so the extra $ for the Lexar 1000x makes no difference on a 7D, same result)
Test 4 (these have an actual image being shot and the ISOs are higher so each RAW file is larger, the performance drops considerably, especially above ISO800 and NOTE that the numbers will vary depending upon the scene shot as different scenes and exposures will produce different file sizes and any given scenario may bump all the numbers noticeably up or down; all are on the Lexar 32GB 1000x card):
ISO3200 5D3 - 20 shots (3.3s) - a big drop from the 35 for ISO100 black frame
ISO1600 5D3 - 24 shots (4s)
ISO800 5D3 - 30 shots (5s)
Test 5 (as above only this time a SanDisk Extreme Pro 90MB/s card was used in all cases):
ISO3200 5D3 - 14 shots (2.3s)
ISO1600 5D3 - 20 shots (3.3s)
ISO800 5D3 - 22 shots (3.7s)
Test 6 (as above only this time a SanDisk Extreme III 30MB/s card was used):
ISO800 5D3 - 15 shots (2.5s)
So yeah for most Canon cameras the Lexar 1000x will not be worth the money at all (unless you are want to pay that much for faster transfer speed to your computer and your computer supports USB3 and you have a USB3 card read that also takes full UDMA 7 advantage) but for the 5D3 wow if you are serious about shooting action and dont want to be saddled with a shorter shooting time buffer than the old 5D2 or 7D then get the Lexar 1000x, suddenly you actually can shoot for longer times non-stop than with the 5D2 or 7D and often by a large margin. So for the 5D3 and action it is well worth it."