Question SATA SSD versus m.2 installed in a PCIe 2.0 1x slot

[PingSpike]

I'm out of ports on my main machine and looking for the least bad upgrade option. I already have a m.2 drive and a 1x PCIe adapter. Normally when you use a PCIe SATA adapter in a 2.0 slot you only get about 375MB/s instead of the 500MB/s of a motherboard port. However, that is because of some overhead of SATA. Would a m.2 in a 2.0 1x slot be missing this overhead and get around the 500MB/s max for the slot? If so there is no reason for me to consider swapping things around to make a SATA drive available instead.

Edit: Realized I was being stupid and I already had a installer with crystalmark8 on it to test this. There is an overhead hit it seems as the m.2 SSD tops out at ~410MB/s not 500MB/s. So it is slightly worse to use the m.2.

 

[Tech Junky]

A picture is worth 1000 words. So, being that 2.0 is ancient in terms of tech at this point I had to look it up.

There's overhead in everything and it gets even harder to gauge where speeds will end up depending on whether the slot is CPU or DMI / chipset bound.

If you have several SATA drives then just get a HBA to mux them through a single slot. Depending on where you have things slotted though will make a difference. HBA's come in a variety of ports per card and different slot lengths as well. IIRC the most ports I've seen on a non-raid or expensive card is 8. Some are really dumb cards and others have controllers on them to yield higher speeds. Cheaper is better though in this case and keep it simple to avoid issues or wasting money.

 

[Seba]

M.2 is just the slot.

Not all M.2 drives are NVMe.
M.2 drives can be SATA or NVMe.

Having said that, even with an M.2 NVMe drive in an PCIe 2.0 1x (via an adapter), your 410MB/s sustained transfer is probably the maximum you can get. But an NVMe M.2 drive in PCI 2.0 1x might still be better for random access than a SATA 3.0 SSD drive.

 

[PingSpike]

Yeah, aside from sequential reads it seemed to do better on all other benches. I decided to go with it since it wasn't really any worse than SATA and I already had the drive.