WD Black SN850 vs SN750

What are people’s opinions in choosing between these two, particularly the 2Tb versions? I have been reading a lot of reviews on them both.

It would be great to have the additional speed of the SN850 and I believe that the motherboard should support the Gen 4 necessary to get that speed.

However, nearly every review I have read of the SN850 talks about it producing very high temperatures. All the reviews have been on using it in a desktop environment and most of them recommend using a heatsink and, indeed, WD has a version that comes with the heatsink. However, I imagine that a heatsink will not be a practicable option in the laptop design of the Framework.

I am torn. What do you think?

I’m a solid no on the SN850 because you’re posting in the DIY section.

My personal opinion is to optimize for power consumption. And in most cases, that also means lower heat.

Unless you’re doing video editing or some other high IO activities, I’m not sure what the extra IO will be used for. On top of that, it’s unknown whether you’ll hit any thermal throttling on a laptop. However, low power consumption, that is important no matter the task.

If you’re optimizing based on power consumption and endurance/TBW, the SK Hynix Gold P31 might be best. But if you’re also looking for higher performance, why not look at the Samsung 980 Pro? It seems to have better thermals compared to the SN850.

Tom’s Hardware has a review of other options also. Considering the multitude of options, why take a risk on running hot?

That’s a good analysis. I did also look at the Samsung 980 Pro but have been put off by the number of people apparently having caching issues - where the cache fills up but does not clear itself - which Samsung seem still not to have cured despite recent firmware updates. I’ll have a look at your other suggestions.

Yes, I put it in the DIY section because I placed my order without an SSD and want to choose my own. I do have an old one to use as a stop gap if necessary.

I think you are right about the SN850.

Personally, I’m using an SN750 because I already had a 500GB laying around.

With what I plan on using this for, I really doubt I’m going to need the theoretical difference between PCIE3 and PCIE4. I don’t even use PCIE4 on my gaming desktop as the 970 Evo in there is still going strong.

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Wow, good to know. It is pretty nuts we have to research so much in 2021. Although I do suppose almost any m2 drives will probably last forever and do just fine for most people.

I was seriously considering the Samsung 980 Pro because of the great reviews by Tom’s Hardware. However, for Linux users, the following review at Phoronix showed pretty poor numbers using the Ext4 files system.

The WD Black SN850 posted much better numbers. So I ended up ordering it. However, I am concerned about it’s high power usage, even when idling. I’m hoping I can tune it so it doesn’t get too hot and/or drain my battery.

I ordered the 980 pro on prime day, it was just too good of a deal and I didn’t read the phoronix test beforehand. My hope is that the new firmware (https://www.reddit.com/r/NewMaxx/comments/n20dm6/samsung_980_pro_firmware_fix/) fixes these issues as well and that I can install it without needing Windows if need be.


Still trying to decide between PCIe Gen 3 and Gen 4 for my SSD. As a non-technical person, am I right that I won’t see any benefit in transfer speeds when I transfer to or from my NAS which has a 1Gb ethernet connection?

What about the 1Tb expansion card I have included in my order? Will the transfer speeds to and from that benefit from a Gen 4 SSD compared with a Gen 3 SSD?

@njf With the expansion card you’ll probably be limited by the USB4 interface before the PCIe interface on the internal drive, and both PCIe gens are much faster than a 1Gbit ethernet connection. 1 gigabit/s is 125 megabytes/s, and the gen 3 drive should do in excess of 3 gigabytes/s.

@Nich_Trimble Thank you. I think I am going to go with the Samsung 970 Evo Plus. It may be ‘old’ but I cannot see myself getting the benefit of Gen4 and I doubt the extra $90 or so is justified for me.

I got the SK Hynix P31 - It’s not as good as the SN750, better than the SN550, and has unmatched power efficiency.
The peak speeds are ~3500MB/s, with a filled SLC cache speed of ~1500MB/s.

Has anybody run own benchmarks?
I just got my framework and inserted a SN850, but with dd I only get a speed of 2.4GB/s.
I thought probably it is not using pci gen4 or something, but I did not find anything in the firmware. It is definitely not thermal throttling, since smartctl shows a temperature of < 60C at the beginning where it is also at 2.4GB/s
I just used

dd if=/dev/nvme0n1 of=/dev/null bs=1G status=progress

I don’t need 7GB/s, but this is kinda disappointing and I dont really now how to debug. Any hints?

Edit: I figured it out, dd is not suitable for this task. Starting multiple dd’s at different postitions of the drive results combined in a lot higher performance.

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Use fio. It’s got all you need to test all sorts of IO workloads. There are sample command line invocations to simulate a few common workloads out there.

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Thanks for that. dd is also subject to distortions because it wants to read off cache if you invoke it more than once. I’ve been using it through many pieces of hardware but its value is now debatable.

“Disks” provides a really nice benchmark that seems to be pretty realistic:

but I’ll be learning fio.


I found where I accidentally did this…you can tell because the number is unbelievable:

Sauron 86a40fa6-82e0-435a-8076-1413fe2edddf # echo 3 > /proc/sys/vm/drop_caches
Sauron 86a40fa6-82e0-435a-8076-1413fe2edddf # dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.86797 s, 278 MB/s
Sauron 86a40fa6-82e0-435a-8076-1413fe2edddf # dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.138753 s, 7.7 GB/s

This is on a USB 3.0 drive.