Lexar 1000x cards: Contradictory benchmark results

[QuickHitRecord]

I have a 5D Mark III at home running the August build (I will refer to it as "Home 5D") and a 5D Mark III at work running the June build ("Work 5D").

I have disabled all modules except raw_rec from both cameras in case they are slowing write speeds. Global Draw is off on both cameras. Through the Canon menu, I have selected S3 as the photo size. LiveView is forced to be always on. Both are set up to record 1920x1080 24fps raw (not MLV). Cards are formatted in-camera (I have also tried formatting them in ExFAT on my Mac, but the write speeds do not seem to show any difference).

For my Home 5D, I have a single Lexar 128GB 1000x CF card (purchased used) that benchmarks at 81.21MB/s. It drops frames almost immediately after hitting the record button. However, the Work 5D benchmarks it at 72.39MB/s, but it can record continuously with this card. How can this be?

Also, I have four Lexar 64GB 1000x CF cards (purchased brand new from B&H) for the Work 5D. They all benchmark between 70.98MB/s and 72.41MB/s on the Work 5D, which seems quite slow for these cards. And yet I have been able to record continuously on them with the Work 5D at 1080P 24fps. Also odd: on the Home 5D, they benchmark at about 10MB/s faster, and allow for continuous recording.

I am very confused. Can someone please shed some light on this?

[RenatoPhoto]

Lexar cards are very good!  I have four 32 GB, one failed a year ago and the rest keep ticking.

Benchmark depends on the file size . My cards do  104 MB/sec with 4096K buffer.

For 5DIII these are the camera settings recommended:

Latest findings to prevent frame drops:

You should check that in Canon Menu:
Image Quality = Raw
Auto Lighting Optimizer = OFF
Long exp. noise reduction = OFF
High ISO speed NR = OFF
Highlight tone priority = OFF
Multiple Exposure = Disable
HDR Mode = Disable HDR

[QuickHitRecord]

Thanks, RenatoPhoto. My 128GB card seems to only be able to do 86.6MB/s at 4096K buffer. I wonder why it is so slow...

I looked at everything that you recommend, and the only thing I needed to change was photo quality (S3 to Raw). At least now it appears that I can record continuously without problems (even though it indicates that I am recording at 91MB/s). It is strange to me that the benchmark numbers do not seem to have much effect over continuous recording.

[RenatoPhoto]

Bigger cards are a bit slower.
Other factors beside card speed influence recording, i.e. CPU.

For the fastest possible recording speed set:
GD = OFF  (overlay menu)
Preview = HaCKed (RAW video)
Indicator display = OFF (RAW video)
Memory hack = ON
Small hack = ON

[QuickHitRecord]

Thank you, I will try these out. I have decided to return the 128GB card. It keeps dropping frames. With the current B&H promotion, I can buy a pair of Lexar 64GB 1000x cards for about the same price that I paid for the 128GB, and I'll be able to take advantage of the warranty. These smaller cards seem to be more reliable.

Also, thank you for working so hard to organize the content on these boards. It would be pretty impossible to find anything if not for your efforts.

[RenatoPhoto]

naaaahhh.  but thanks!  many people contribute to this board.  I do it to pay back what I get out of it!!!