I have a fair bit of experience with NVME but not as extensive as I have with SATA/SAS devices.
To answer your question first, how much space do you need on the solver machine? If less than 200GB, go for the 970 evo plus. That being said, while I'm a huge advocate for fast storage, I don't think this particular workload is going to be storage bound most of the time. Biggest solve time upgrade would be upgrading to Ryzen 3900x or 3950x to add 50 or 100% more cores, though at significant cost.
I've been out of poker since before solvers were really a going concern, but my understanding is that standard operation is for the entire tree to be loaded into RAM while calculating. Running some quick estimations, the load time for a 10GB file at 450 MB/s for SATA would be 22.75 seconds and for NVME at an estimate of 2GB/s would take 5 seconds. That's a substantial speed up percentagewise, but assuming you're manually reviewing the results afterwards, the time your storage bound is likely to be miniscule compared to the time your compute bound waiting on the solve. You've already hit the practical max for RAM on this rig, so the standard buy more RAMs advice doesn't apply
Not sure on pricing and availability on your side of the ocean, but over here the Intel 660/665p QLC drives are back to around $100-120 for 1TB. These aren't in the same class as the Samsung NVME, but at the price I've recommended people choose these and then format them as an 800GB drive. This works around the tanking performance as a QLC drive gets filled up and loses its ability to use pseudo-SLC caching. As an 800GB drive, pricing is still pretty good. Drive endurance hasn't been a practical problem in the consumer space in my experience, though some of the new QLC drives may put that position to the test if run nearly full all the time.
Now to NVME in general. NVME basically shines everywhere vs SATA flash, there's not even a ton of price premium anymore. SATA drives have been pretty stagnant performance wise since they were able to saturate the bus several years ago. SATA protocols were written around the performance characteristics of spinning disks, perfectly reasonable at the time they were adopted. NVME uses a different set of disk commands designed fully around addressing flash memory. The bus bandwidth allows for much higher peak speeds and mid to high end NVME controllers are more powerful, allowing for better random read and write perf in addition to sustained read and write perf.
I own desktops that boot from an Intel 905P Optane drive and a WD Black 1TB drive, both are quite fast. I bought the Optane drive back when NAND flash was running about double the price it is now, so it was a choice between a 480GB Optane for $500 (MSR$600 minus an ebay coupon) vs a Samsung 970 EVO for $400-$450. Now that you can get a Samsung 1TB 970 EVO for around $200 and the Optane is still $600, I wouldn't be able to pull the trigger. Optane is faster at queue depth 1 and in certain other scenarios but its not meaningfully faster than NVME NAND for a lot of general usage to justify the current 6x price per GB premium.
My laptop has an OEM Samsung 1TB TLC NVME drive similar to the 970 EVO. It benchmarks well and I've been happy with performance in general.
My standard recommendation for NVME client drives has been 970 EVO/WD Black for performance systems/when it fits in budget. The Intel 660/665P drives can fit a niche in delivering NVME to a more budget constrained system.
For workstation and NAS usage, I like used enterprise drives, preferably in the 2.5" SATA or u.2 format. Enterprise m.2 drives are usually 22.110 sized which many non-server boards and even some server boards don't have long enough slots for. SSD power loss protection is really important when data integrity is crucial and you basically have to get enterprise drives to get drive level power loss protection, which a UPS can supplement but not replace. My previous job ran a lot of Intel DC3610 800GB SATA SSDs. They were super reliable and while not barn burners compared to client NVME drives, were super consistent and way faster than the 10K 1.2TB SAS drives they generally replaced. They're now pretty darn cheap on US Ebay.
Last edited by headtrauma; 04-29-2020 at 12:51 PM.
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