topic Re: 64GB G series UHS-II SDXC wont write to specified speeds? in Alpha & NEX interchangeable lens cameras

64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Sun, 07 Jan 2018 10:33:54 GMT

Hi everyone - first post!

Sorry if its in the wrong section, I couldnt find a memory card area.

Q - I have a SF-G64 SDXC card which wont write anywhere close to the 299mb/s advertised speed?

I ran a Black Magic speed test (using a Sandisk UHS-II adapter) and the maximum write speed I could get after a 5GB stress test is 185.9mb/s.

Is this normal as I paid a pretty penny for two of these G series cards and have heard the M series perform pretty much the same and for half the price!

I posted a screengrab below!

Thanks in advance!

SF-G64

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

Drewde — Mon, 08 Jan 2018 10:00:05 GMT

Hi,

Can you please let me know what camera you're using.

Thanks,

Drew

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Mon, 08 Jan 2018 10:34:03 GMT

its the Panasonic GH5 (with dual UHS-II slots)

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

Drewde — Wed, 10 Jan 2018 09:04:52 GMT

Thanks. Did you just run the speed test once?

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Wed, 10 Jan 2018 09:31:55 GMT

I think the BMST did about 8 or 9 passes (but maybe more) both on read&write at 5GB stress limit.

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

IamNic — Thu, 11 Jan 2018 00:30:34 GMT

Hi @funomoly,

does the stress test write data from the RAM (creates it on the fly) or does it write a sample file stored somewhere on the harddrive/SSD?

I am not familiar with that particular speed test.

If so I would say the reason is, that the sample file can't get read faster from the drive.

If that is not the case (the file/data get's created on the fly), I assume your USB ports cap out at the shown speeds for some reason.

Also if you use the GH5, I am curious, why you bought such overly fast cards anyways - if I am informed correctly, it records video at 400Mbit/s (4K 4:2:2 10bit) max, which is exactly 50MB/s.

- Nic

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Thu, 11 Jan 2018 23:29:20 GMT

Hi IamNic!

I assume the stress test is done from the RAM as it doesn't use any stored files to run off from.

Its interesting that you mention the USB port capping out at a certain speed - however both my windows (gaming) laptop and macbook have USB3 ports which I connect the card to via a Sandisk UHS-II adapter. Surely there should not be any capping if my read/write speedtest scores are consistent over both hardware systems?

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

IamNic — Thu, 11 Jan 2018 23:38:42 GMT

Hi @funomoly,

that depends on the chipset of your machines.

I have heard of transfer-speeds as low as 160MB/s on some USB 3.0 ports.

Here's an interesting article about port benchmarks: https://www.macworld.com/article/2039427/how-fast-is-usb-3-0-really-.html

- Nic

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Fri, 12 Jan 2018 11:16:19 GMT

Thanks for the link - interesting read!

So its the CPU / GPU combo that will determin if the card can reach its advertised read/write speeds? This does makes sense. Ill try testing on newer model and see what happens.

(Also, which stress tester do you use - could be BM giving me incorrect data speeds?)

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

IamNic — Fri, 12 Jan 2018 11:59:26 GMT

Hi @funomoly,

I use CrystalDiskMark.

Though I doubt the BM benchmark gives you wrong readings.

I hVe to ask again - why did you get such fast cards for a camera, which doesn't write faster than 50MB/s?

- Nic

Re: 64GB G series UHS-II SDXC wont write to specified speeds?

funomoly — Fri, 12 Jan 2018 14:08:44 GMT

Hi Sorry forgot to answer that - Yeh I bought the cards after a long search on what would work on my GH5.

I already have a 64GB 95mb/s Extreme Pro sdxc card and that stopped recording video after 13minutes at 4k 8bit.

Next up was the 64GB Transcend sdxc card - same thing but cut out after 5minutes again at 4k 8bit.

Now, I'm on the Sony G 64GB which is the only card to not cut out on me in 4k 8bit (2hr40mins record time) but now I can record 4k 10bit (1hr40mins).