We're not anywhere near the point where going from SATA to M.2 "feels" like going from platter to SSD.
What really matters for gaming is random read performance for small files at a very low queue depth*. Here's a typical CrystalDiskMark result for a PCIe v3 Samsung 970 (NVMe):
Samsung (and everyone else) advertises that maximum sequential speed up at the top (3.5GB/s - which is close to the maximum for PCIe v3) in all their ads, but for gaming the metric that matters most is that 4kQ1T1 number down at the bottom, which is only ~65MB/s! So how much of a difference does PCIe v4 make? Let's look at the Samsung 980 (NVMe):
Wow, that top speed is almost double, right? 6.7GB/s is close to the 7GB/s max for PCIe v4, but again, when you look down at the 4kQ1T1 numbers, we're only at ~88MB/s, which is only about 33% faster than the PCIe v3 970.
And what does a decent SATA SSD look like? Well, here's Samsung's SM951, which is not technically a SATA drive (it's AHCI), but is the absolute highest performance you're going to get from any SSD that
doesn't use the newer NVMe protocol:
Ooo, almost 50MB/s of absolutely
scorching /s 4kQ1T1 gaming performance. For the record, decent SATA drives clock in right around 33MB/s of 4kQ1T1.
So yeah, like Gas says, in the transition from SATA-III SSDs (max theoretical of 600MB/s) to PCIe v4 NVMe SSDs (max theoretical of 7GB/s), the metric most relevant to gaming performance has actually only gone up about 3x or so over the last 15 years.
...and now I'm gonna talk about Intel's "Optane" drives, which use a different method of storage that actually DOES improve gaming performance. Just how much? Well...
Okay over 200MB/s of 4kQ1T1 --
now we're talkin', right? Well...not so fast. Optane drives are ridiculously expensive compared to "regular" SSDs, and Intel stopped selling them to consumers anyway back in Feb 2021 so sorry, no blazing fast Optane gaming for
you unless you want to buy used 280GB drives at about $600 ea or brand new U.2 enterprise 1.6TB drives for $3500. No that is
not a typo.
EDIT: Reuploaded the pics with ones that indicate which line is the important one.
--Patrick
*The system can request multiple files, sometimes faster than the drive can respond (especially with HDDs). When the system requests things faster than the drive can fulfill those requests, that's when the "queue depth" piles up. A really fast drive will respond so quickly that the queue
can't pile up much beyond QD1, so all these QD32 numbers are meaningless and only good for benchmark scores and marketing.