MS All Models M3 Ultra – Only 400MB/s RND4K QD64 on 2TB SSD? Normal?

[everestsky]

Just got my M3 Ultra (28-core) with 2TB SSD yesterday, and I’ve been running some disk benchmarks using AmorphousDiskMark with the default settings from the app store. The RND4K QD64 read speed is consistently around 400–450 MB/s, after several tests.

I’ve seen others in other posts post results showing 1100+ MB/s for the same test on similar setups, 1TB or 2TB. Wondering if this is normal for my 2TB version or if I might be missing something?

• Tried running tests multiple times, results are stable around 400 MB/s, occasionally 380+ mb/s.
• No other heavy apps running during the test, just this benchmark app
• System is not overheating or throttling.

Is this just how the 2TB drive performs, or could there be something wrong? Would appreciate if others with M3 Ultra could share their RND4K QD64 numbers for comparison or insights.

 

[Adora]

A little off topic but 4TB in my M4 Pro mini looks like that:

Even my M3 iMac with 1TB is over 1000 in the part you mean:

P.S. This app wasn't available in my country by the way. I wonder why they don't put in on their website when it's free and small (1.4MB only and zipped even less). But if you search you'll find a copy very easy.

It's also not in Homebrew since December:

"Cask 'amorphousdiskmark' has been disabled because it is now exclusively distributed on the Mac App Store! It was disabled on 2024-12-16"

 

[Chancha]

Even a M2 base model 256GB with only one NAND is getting 600-700 on random 4k QD64. Something is not right with your unit.

 

[Surenmunoo]

This is from M2Max with external boot SSD. Something is off with yours.

 

[MacPoulet]

Has Spotlight finished indexing? Are you testing this right out of the box?

 

[everestsky]

A little off topic but 4TB in my M4 Pro mini looks like that:

View attachment 2503417
Even my M3 iMac with 1TB is over 1000 in the part you mean:

View attachment 2503419
P.S. This app wasn't available in my country by the way. I wonder why they don't put in on their website when it's free and small (1.4MB only and zipped even less). But if you search you'll find a copy very easy.

It's also not in Homebrew since December:

"Cask 'amorphousdiskmark' has been disabled because it is now exclusively distributed on the Mac App Store! It was disabled on 2024-12-16"

thank you for the testings! i also ran the test on my imac 2019, 512 gb and got 1100+ RND4K QD64 read. Not sure what happened. Maybe because of m3 ultra chip? Hope someone can help run the tests on their m3 ultra units and provide more data points.

 

[everestsky]

Even a M2 base model 256GB with only one NAND is getting 600-700 on random 4k QD64. Something is not right with your unit.

The base version like 256gb or 512gb may have more advantage on random read and write. I hope to get more data points from m3 ultra or maybe m2 ultra.

 

[everestsky]

This is from M2Max with external boot SSD. Something is off with yours.

View attachment 2503518

i have a 4TB SSD Samsung 990Pro using an external enclosure, which also has more than 1000mb/s on rnd4k speed. 990 PRO is a really good ssd.

 

[everestsky]

Has Spotlight finished indexing? Are you testing this right out of the box?

i ran the test right out of the box when there was no spotlight taking more than 1% CPU. I also ran the test after excluding the whole internal SSD from Spotlight in the setting and restarted the Mac, the result was similar, around 400+mb/s

 

[splifingate]

Is this just how the 2TB drive performs

From my M2 Max AP2048Z, today:

IIRC, I consistently get RND4K-QD64 readings ~970

I get ~1,350 on my Thunderbolt/USB/4 Externals

 

[everestsky]

From my M2 Max AP2048Z, today:
View attachment 2503652
IIRC, I consistently get RND4K-QD64 readings ~970

I get ~1,350 on my Thunderbolt/USB/4 Externals

Thank you! This makes me suspect the Ultra chip might indeed be the key factor. It would be great if more M2 Ultra and M3 Ultra users could share their experiences to confirm this.

 

[Chancha]

https://www.reddit.com/r/mac/comments/1gvovdt/the_ultimate_guide_to_mac_ssd_speeds

Okay now this thread reminds me of this reddit user’s compilation of various Apple Silicon SSD speeds, his graphs include M1 Ultra and M2 Ultra as well. Together with your M3 Ultra test results, it is safe to conclude there is some penalty introduced by having parallel storage controllers on the Ultra dies. Can this be a similar phenomenon with stripped RAIDs sometimes having poorer read performance than even a single disk, if fragmentation is too intense.

Previously when I saw that thread I didn’t pay attention to the QD64 at all since I was not a Ultra-tier target audience, and then pretty much everyone was more concerned with sequential during the M2 NAND “scandal”. Well the good news is there is nothing particularly wrong with your M3 Ultra unit, the bad news is then of course if your work is bottlenecked by QD64 then it is a huge undocumented bummer.