Getting highest sustained write by using gen4 into a gen3 system ?

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Docop

Member
Jul 19, 2016
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Hi

I want to know if we can get the highest sustained sequential write, by using an nvme Gen4 into a gen3 slot. On the transfert and ref, with a samsung gen3 970, after 20sec of 3gbps it drop to 1.5gpbs for the rest of time(after 2,4,9min). So no dram effect and we see an usb10g give about the same speed. But for a FireCuda 530 / Adata Legend 960 or Sabrent Rocket 4 : sustained is at 3.8gb for 4min And on the samsung 990 it's 1.4gbps.

So with the Firecuda, Adata or Sabrent (all gen4 nvme) put into a gen3 slot = will they fully give a continuous sustain speed of about 3.6gbps , maxing out the pcie bus fully ?

Thanks
 

azev

Well-Known Member
Jan 18, 2013
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If you want to maintain sustain write throughput, you want to use an enterprise class SSD. Most consumer SSD only allow momentary burst of speed until its SLC cache is exhausted then the speed would drop by a big margins... Some lower end SSD would even slow to a crawl once the cache is full.

Your idea of using nvme gen4 drives on a nvme gen3 slots will not change the fact that most, if not all consumer drive will slow down when the cache fills up. If anything, you might extend the time that it can burst at max speed due to rate limit imposed by the gen3 slot.
 

CyklonDX

Well-Known Member
Nov 8, 2022
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Most drops on the performance on nvme's is due to temps crawling in.
Going gen4 to gen3 typically cuts power usage, temps, top bandwidth in half.

Next question one would have to ask themselves (and test) full disk write ~ is flash the same speed throughout the whole disk. (Most often its not.)

(for most stable and linear bandwidth one should use gen4 nvme in pcie gen3, and put some heatsink on it; Keep in mind consumer grade nvme's do not have great endurance - if you plan on using it for a lot of writes - this isn't solution for you unless you want to fork out big chunk of $ for higher end enterprise grade part -- zfs with big chunk of ram might be a better solution for you.)
 
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