[Samsung Galaxy Note 9 Questions & Answers] 6thtry:
MicroSD card speed tests on Note 9 Exynos (and Tab S3 and PC)

The 5 cards finally arrived (and I'm expecting 1 more tomorrow, 2 last ones some time next week). Today's cards were Sandisk Ultra, Extreme and Extreme Plus, and Lexar High Performance 633x and Professional 1000x.

Their results are now in the google sheet, and it included already couple other results I did not mention in between, for the Kingston Canvas Reacts.

(Edit: some more have been added since that. Still on the way are Samsung Evo Plus 256GB (for a cheaper(?) test if the 128 vs. 256 GB capacity makes any difference on those - seems it can, see Sandisk Ultra 128GB vs 256GB), and Sandisk Ultra 400GB and Kingston Canvas React 512GB... uh, for, just, yeah, big and something.)

128 GB Verbal results

Remember, these are considered as "with my Exynos phone" only, not considering e.g. read speeds on external reader, or on Snapdragon, etc. , and speeds as "new, unused" (the rates will deteriorate as they get used). Prices from Finnish shops or Amazon.de (results sheet shows cheapest price). (I also checked amazon.co.uk, but some products are not delivered to Finland, and no free delivery to Finland, unlike from the de-site. And in desperate cases, like Lexar, I just googled anywhere...)

Lexar Professional 1000x (U-II 3, V60) is also 'murder' (like Adata) when it comes to random writes. As in, at first I thought that I'll only run the Micro-test twice (not 3 times) because it was so slow, but as it was s l o w l y going on, I decided that first run shall be enough. In the time it takes one pass (of 3) of the random write test, I have run through all of the Micro-test on any other card (if not 2-3 times at that). That card is to be reserved for large photos/video shooting, i.e. sequentials only, where it might work very nicely. And probably not on this phone, as the other cards can get close enough in sequentials for a fraction of the price. (Of course, read speeds in a proper reader might be another story, if that matters.)

(Also, this card was the first that didn't work on first insert, I had to reinsert the holder to get it work. Could be a slim card, could be the many inserts I have already made, or just a random thing.)

Note though that this card did reach the very high sequential write speeds, like Adata.

Goes to the DSLR bag...

Sandisk Ultra seems to be the best "bang for buck" in the 128GB category, from the cards I've tested. It has the worst random write rates, but hey, still clearly passes A1 rating. NOTE: the specific model may matter, there are many "Ultra" series, so pay attention to this: "SDSQUAR-128G-GN6MA". (Though the last part of that code varies per market area.)

(All 4 Sandisk card types are very similar in speeds, so much so that I don't see any point in buying any other than the Ultra. That is, if not considering external reader speeds, too.)

Kingston Canvas React looks to be the next step up, if random write speeds are important. It has the worst sequential write rates, but still reaches above 30MB/s, so plenty enough, and juuust barely touches A1, but overall still nice for the double price (compared to Ultra).

Lexar High Performance 633x (EDIT: ) and PNY Elite-X. Look at those random read and write rates! The only cards way above every other 128GB card I tested. Considering that it is priced around the same level as Sandisk Extreme Pro and Plus (which should be A2!) (Edit: and even lower price for PNY), I think these are keepers. On my PC/reader most other cards get about 92/80 speeds, Lexar (edit: and PNY) still reached 92/66, and on the PC, its the first (read) speed that mostly matters, moving all the photos and videos to PC.

(Note: PNY Elite-X seems to be sold with two slightly different product codes, the one I tested ends "WX-GE", not the PNY's official "100EX-GE". No idea if there are performance differences, or if it is just about e.g. packaging.)

(Edit: 27th Dec, I measured this earlier but forgot note about this interesting result: Notice how the Lexar 633x can give about 50% higher random write rate when connected to the phone through OTG adapter, MobileLite G4 and UHS-II adapter. Though everything else is much slower that way.)

Samsung was left at "meh". Buy Sandisk Extreme instead, same price, mostly better. Especially the Amazon's Evo Selects (which were supposed to be just rebrands of Evo Plus) have given lower random rates (in all platforms).

Adata Premier One (U-II 3, V90) is 'murder' with random writes (like others had already gotten). And like the Lexar 1000x, this Adata card reaches very high sequential write rates (highest of all tested so far), proving what the phone could do if all things are just right. Goes to the DSLR bag...

Numeric results

https://docs.google.com/spreadsheets/d/1rs8S2yreJYYms6ik8NgoGagZ_6OKrU5bu1FotHJVz6g/edit?usp=sharing

The other sheet has now some of the extra info for cards, may or may not be of use, but at least the links to manufacturer product pages in there should be of use.

128 GB averages for quick read:

Name/model . . . . . . . . . . . . . . . . . . price . . . . read . . write . . read IOPS . . write IOPS

Kingston Canvas React . . . .	. . . . 43.90 . . . .. 71.0 . . . . 34.1 . . . . . . . 1,500 . . . . . . . . .. 743

Sandisk Extreme Pro . . . . . . . . . . . 51.98 . . . . 72.3 . . . . 48.3 . . . . . . . 1,470 . . . . . . . . . 628

Sandisk Extreme Plus . . . . . . . . . . 59.25 . . . . 72.4 . . .. 46.7 . . . . . . . 1,430 . . . . . . . . . 624

Sandisk Extreme . . . . . . . . . . . . . . . 35.41 . . . . 72.5 . . . . 47.9 . . . . . . . 1,440 . . . . . . . . . 601

Sandisk Ultra . . . . . . . . . . . . . . . . . . 22.93 . . . . 73.3 . . . . 43.6 . . . . . . . 1,660 . . . . . . . . . 560

Samsung Evo Plus . . . . . . . . . . . . . 33.90 . . . . 66.0 . . .. 38.0 . . . . . . .. 1,260 . . . . . . . . . 685

Samsung Evo Select . . . . . . . . . . . 33.99 . . . . 70.0 . . .. 38.0 . . . . . . . . 1,180 . . . . . . . . . 610

PNY Elite-X . . . . . . . . . . . . . . . . . . . . 44.39 . . . . 74.7 . . . . 41.7 . . . . . . .. 1,870 . . . . . . . 1,080

Lexar High Performance 633x .. 55.99 . . . . 74.5 . . . . 42.1 . . . . . . .. 1,810 . . . . . . . 1,080

Lexar Professional 1000x . . . . .. 132.80 . . . . 70.6 . . .. 54.8 . . . . . . .. 1,390 . . . . . . . . . . 40

Adata Premier One . . . . . . . . . . . . 91.00 . . . . 70.6 . . .. 56.4 . . . . . . .. 1,320 . . . . . . . . . . 68

(WTB table tag support to this forum.)

256 GB

Kingston Canvas React essentially the same speeds as the 128 GB, so, it is simply twice the price = twice the capacity.

Sandisk Ultra gives otherwise same results as the 128GB version, but sequential writes give most of the times much lower speeds. It can, with a lucky 1 in 4 runs, give the same speed as the lower version. (On Tab S3 it gave the same or even much higher than 128GB model, on PC the same... so it just seems to be inconsistent with that parameter.) Also, on one run it gave significantly higher random read rate than expected.

Samsung Evo Plus essentially the same speeds as the 128 GB, and with similar quirks as those 128 GB variants, too. So, it is simply twice the price = twice the capacity.

Lexar High Performance 633x is not as good as the 128GB version of it on the random read/write rates. (Or at least this Amazon variant is not as good.) Still overall better than the others, but considering its high price, maybe not worth it.

Their numeric results are (or will be) in the google sheet.

Other stuff

400GB and 512GB variants will be in the google sheet (and possibly mentioned in the comments below).

ADDED 2nd Dec: Made couple measurements with each card (except the Lexar 1000x, just one for it) on my Tab S3 which has Snapdragon 820, and added the results to the google sheet for comparison. Sequentials are mostly the same or just tiny bit better on it, random reads often a lot better, random writes typically about 10% better, than on Note 9 Exynos. The main thing out of those tests was to check which parameters are not bottlenecked by the card, but the phone.

But, the tests also revealed that not all cards/parameters have relatively higher results the same way. For example, the Samsung Evo Plus 128GB has relatively much higher random read rate difference than other cards. And only the Lexar 1000x has noticeably higher sequential write speed, yet was only card that does not have noticeably better random write rate (excluding Evo Select 128GB as its values are questionable to begin with). Interesting, but such technicalities won't help an end user.

ADDED 2nd Dec part II: Made some measurements with each card on my PC, using USB 3.0 (with long cable) and Kingston MobileLite G4, CrystalDiskMark 6.0.2 default settings except 3 runs and 50MiB, sticking cards in the microSD slot. The Lexar Professional 1000x was also tested with the UHS-II SD-adapter it came with on the reader's SD slot (which supports UHS-II, unlike the microSD slot). Added the results on the sheet.

Most interesting results from the PC side are:

Lexar 1000x could do about 10x better in the random writes.

Lexar 633x can do very high random reads and writes, above A2 ratings.

Kingston Canvas Reacts' have lower random read rates on PC than on my mobile devices?

Samsung Evo Plus manages to give comparatively better results on PC than on my mobile devices. Not so "meh" in these results.

Almost all cards behave like roughly 90/80 on my PC via UHS-I interface (except those rated for lower), but Adata can reach 170/160 through the same system/connection/reader on the UHS-II interface (with UHS-II SD-adapter), so I'm assuming the reader microSD side bottlenecks to around that 90MB/s read speed. It might also bottleneck the seq write speed to a bit over 80MB/s.

From both Tab S3 and PC results combined, it seems that the Samsung Evo Selects are NOT rebranded Evo Pluses after all. Or maybe that "select" refers to Amazon selecting the bad ones, buying them cheaper from Samsung and selling for higher, while making claims "there is a newer version of this product" on their Evo Plus product pages linking to the Selects. Granted, my test set is small, only 2 comparisons cases, could be just two cases of bad luck.

ADDED 3rd Dec: Results for Adata Premier One 128GB and Sandisk Ultra 256GB. The Adata managed to give quite impressive sequential results on my PC; on other platforms it is comparable to the Lexar 1000x. Yet quite a bit less expensive.

ADDED: 4th Dec: Results for Samsung Evo Plus 256GB and Kingston Canvas React 512GB. Samsung speeds are similar to the 128GB variants (both in good and bad), so twice the price = twice the capacity. The Kingston 512GB, however, had some suprises. Much faster sequential writes than 128/256GB variants, but its random write rates dropped a lot after the first run. Also, its sequential write speed on the PC is really bad, I had to measure it multiple times (even with another card test in between). It just doesn't like my PC/setup.

ADDED: 14th Dec: Results for Sandisk Extreme 400GB and Sandisk Ultra 400GB. Both seem to be similar to the lower capacity variants. Ultra shares the seq. write issues of the 256GB variant, and has problems on seq. writes with PC, like the Kingston Canvas React 512GB.

ADDED: 21st Dec: Results for PNY Elite-X 128GB. Basically the same card as Lexar High Performance 633x, PNY is just a bit cheaper.

ADDED: 7th Jan: Results for Lexar High Performance 633x 256GB. Good, but random rates, especially random write, are quite a bit lower than on the 128GB model.

P.S. family shot as an attachment (missing the PNY and Lexar 633x 256GB).