Why would Samsung NVMe M.2 run at only half of max speed?

bobkn said:

Sorry. I tend to prefer colorful turns of speech, sometimes, over more appropriate ones.
However, adding an SSD in the form of an NVME drive in an M.2 to PCI-E adapter goes beyond the practical. Mostly. You were sensible to use a SATA drive.

My main computer has one M.2 slot. I installed an M.2 NVME SSD in it. However, I had another M.2 NVME SSD that I happened to have and wanted to use. I bought a M.2 to PCI-E adapter for this drive. The sequential read speed is about 1600 MB/s. The expected speed if it was installed in the MB M.2 slot would have been about 1800 MB/s. BTW, the adapter is plugged into a PCIe 3.0 x4 slot.

MisterEd said:

My main computer has one M.2 slot. I installed an M.2 NVME SSD in it. However, I had another M.2 NVME SSD that I happened to have and wanted to use. I bought a M.2 to PCI-E adapter for this drive. The sequential read speed is about 1600 MB/s. The expected speed if it was installed in the MB M.2 slot would have been about 1800 MB/s. BTW, the adapter is plugged into a PCIe 3.0 x4 slot.

I presume that you used the SATA SSD in an older system with no M.2 slots.

The main potential issue in using an M.2 to PCI-E slot adapter is when you use an NVME drive in a system with a BIOS that doesn't support booting from NVME. (Assuming that you want to boot from the NVME drive.) There are supposed to be fixes for that, including a modified BIOS. I've never done that.

I used an M.2 drive in an adapter as a boot drive in a system with no M.2 slots. The M.2 drive was PCI-E X2 rather than the X4 that is common now, and it wasn't NVME, so there no problem. Still faster than a spinner. I don't see a lot of non-NVME PCI-E M.2 drives on the market any more.

Although the posts above are wise, I just wanted to notify the world that, in my test Dell Optiplex 7010 Mini-Tower:
- I have FINALLY replaced the original i3 processor with a used i7-3770 that I bought on eBay,
- I now have PCI-E 3.0 in the x16 PCI-E slot, and
- my M.2 NVMe is showing the full expected speed of 3,400 MBps per the article I linked to above.

It's alive !!!

This is on my test used Optiplex 7010 Mini-Tower, which might become a fourth computer in my wife's mini-office.

Now, my personal computer is also an Optiplex 7010 Mini-Tower with its original i5 3470 and HDD. I wonder whether that i5 would also provide PCI-E 3 in the x16 slot.

On the now-fast i7 NVMe M.2 test machine, CPU-Z's Motherboard tab says "Bus Specs. PCI-Express 3.0 (8.0 GT/s)"
On my personal i5 HDD machine, CPU-Z's Motherboard tab has "Bus Specs" greyed out with no info showing.

Questions:

1) Any thoughts on whether an i5 will already provide the needed PCI-E 3 in the x16 slot?

2) Are my power supplies enough to handle the faster i7 CPU? I imagine yes because that i7 was always listed as an option for the 7010, but what do you think?

I might get around to checking out pcie adapters on a 310 motherboard.