Clarification on SD Card size limit (32Gb?)

Just wondered if the SD card capacity limit was a physical one with the board or just a logical one that could be circumvented

Starting to get harder to buy smaller SD cards, Amazon UK only has a very limited supply of branded / trustworth sellers of Sandisk and last time i checked a couple weeks ago none of things like Kingston Canvas cards which we know perform well.

Just wondering if the 32GB limit was hard and fast or whether you could use a 64GB with a primary partition of 16GB… so wasting the rest of the card, but would that work in a proffieboard?

My other issue for needing WAY more cards than i have sabers is that i’m finding the cards are getting an ever higher failure rate and degrading on read speed to the point of causing performance issues on the board (i reformat each time i copy onto the card)… had at least 4 fail on me this year including a couple which were DOA (or too slow on arrival to perform enough)

As I understand it, the larger SD cards have much slower read speeds and with ProffieOS the read speed is much more important. Personally I only run 4 or 16GB cards in my various sabers. It’s more important you have a card that can be read fast otherwise you’ll get lag in your effects and styles.

There does seem to be a correlation to the global component shortages and more “crappy” cards in the marketplace. All of my cards I have from before the pandemic are still kicking wihtout issue but I’ve had a handful of cards I ordered more recently that just aren’t equivalent either in read speed (even from same manufacturer) or simply crapping out.

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But is there a fundamental reason (performance aside) about the card size or partition limit?

For the past 2 years i’ve ALWAYS bought Kingston Canvas Select Plus but i’ve had to replace at least 4 of them now as they just started causing issues and when i tried formatting and copying on again i noticed the speed had dropped at least 50% to what a “good” card performs at

I just managed to pick up another 4 from eBay so while i think i’m ok, the fail rate has just been appalling for me this year.
Amazon just has an endless supply of who-knows brand like “Gigastone” or “Qumox” …
But smallest kingston i can get now in UK is 32GB.
They just don’t have 4/8/16 anymore at all and 32’s are starting to get more tricky to pick up

I’ll defer to anyone with more knowledge, I believe the larger size inherently is slower to read because there’s more on it, thereby affecting performance.

I’m not actually sure what the limit is. I think cards up to 1Tb should work as long as they don’t change their protocol in some weird way. There may be limits within fat32 that prevents larger file systems, but I don’t actually think so. I have personally tried 128Mb cards, which work just fine.

Larger cards tends to use smaller flash cells and more bits per cell, which can lead to slower read/write speeds, but as technology improves, this issue starts to go away. It used to be that cards that were 16Gb or smaller were more reliable, but I’m not sure that’s the case anymore. I suspect that the new sweet-spot is somewhere around 64Gb.

My recommendation is to look for “high endurance” or “industrial” SD cards. They may not be the fastest cards on the market, but they seem to have less problems in the long run.

Ideally, SD card manufacturers would publish TBW values in the same way that SSD manufacturers do, as that would give an indication of how “durable” a particular card is, but unfortunately that is not common practice yet.

There is nothing in ProffieOS that makes large SD cards slower. (that I’m aware of) So if you find a large, fast, cheap and reliable sd card, there is no reason to go look for a smaller one.


Ok bizarre… must be one of those “myths” handed down between proffie users… i’m sure i was told as true that the proffieboard or OS couldn’t handle larger cards

But thanks… will try and start looking for high performing alternatives… the death rate is just getting irritating for the Kingston 32’s i’ve got

The fact that no one seems to be able to get a card more than 32GB to work reliably seems like a clear issue beyond that. This comes up regularly and regardless of a technical explanation, if you want your board to work properly, less than 32GB is the advice. I’d say 16GB is the sweet spot from experiences in the community. If anyone can show a 64GB+ card working in a Proffie, I’d be happy to defer.

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I’ve been using a 128Gb card for most of my testing for quite some time now. (1-2 years)


Fair enough.

FWIW here, I run 64gb SanDisc(s) on anything I have that’s running 6.7 with Edit_Mode and have had ZERO lag issues with 66 font packs in the folder. Any prior concerns as to speed and function have been resolved as of 6.6 since it had nothing to do with the SD cards. YMMV so all I can say is do as advised before and as I did, run the serial monitor test and look for at minimum (IIRC the “magic numbers” are 1000 and 10 as to the report printout) so you know you have a solid card.

**The 64’s were as a bulk offer (5 but limit was at the time 10) via BestBuy months back, it may still be up as an online coupon.

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Which ones you using? Extreme/ultra etc

The Ultra but not the new white with gold “Ultra”. The standard black and red and grey and red, they sent me both styles. Like $11.00 each, NewEgg has some.

I dont think there is any real benefit for getting a card over 32GB. If you get anything larger (64gb, 1tb, etc) …once you format it to FAT32, it renders your card down to a 32gb size anyways (or at least thats whats happening with my larger cards)

I just stick to any brand that is 32GB or less, and is class U10 or V30 to ensure the read/write times are good.

The maximum volume size for FAT32 is 16Tb I think.
What formatting program are you using?

Im using a tool called AOMEI Partition Assistant (standard Edition)

If it can’t make fat32 partitions over 32Gb, I suggest trying a different program.
(Like maybe the SD association formatter.)