Best use of a U.2 connector on my motherboard?

You do realize that the QVL list is only whatever they happen to have on the shelf at time of testing right?

Ghot said:

You mean they don't just use really long wires ?!?


You do realize that all these companies live right down the street from each other, and that it's to their advantage to get their new products tested on as many motherboards as they can... right?

Really? I think of Asus as Taiwanese. Samsung is definitely Korean. Am I being too literal?

Non-rhetorical question: has anyone had an NVME M.2 drive fail to work in a motherboard with an NVME M.2 slot?

It never occurred to me to check the QVL for an M.2 drive. So far, no issues. (I've used a total of 3 NVME M.2 drives, I admit.)

Ghot said:

Too literal.

Most NVMe M.2 drives are PCIe 3.0. The 980 Pro is PCIe 4.0... which allows speeds approx. twice as fast.

It's like the RTX vid cards. The X570 chipset is PCIe 4.0 capable. So, last year I rushed out and bought an RTX 2070, only to find that the card itself is only PCIe 3.0 capable. The Nvidia 3000 series cards are PCIe 4.0 capable.


(snip)

Do PCI-E 4.0 graphics cards offer a practical advantage? I suppose if you were short on PCI-E lanes, you could run one at X8 on a 4.0 motherboard, for about the same net bandwidth as 3.0 X16.

The 4.0 M.2 NVME SSDs show higher speeds than 3.0, in benchmarking software. Probably little real-world advantage.

If you check my primary ssystem specs, you'll see that this ain't sour grapes.

Ghot said:

Yes, I have seen that... this is the cable they mention...

Amazon.com

Attachment 336663




And this is the connector(s) on the back of the HDD...

Attachment 336664




I know it's hard to tell from these pics, but I don't think this cable will work?
I dunno... maybe the huge female connector on the far right of that cable.. . ??


This is the part of the connector that worries me...
Otherwise, it looks like it will work.

Attachment 336666





And yeah, I did think about a PCIe card, but then I'd have cable(s) running "across" the motherboard.
If I use the U.2 connector I can avoid that...


Attachment 336667







I guess I could get a PCIe card and a black SATA cable, and run the cable like this... ??


Attachment 336668

You can most certainly attach a SFF-8639 receiver to a SATA drive interface.

The cable you're looking at is a SFF-8643 (Historically this is mini-SAS port connector. However, this is now dual-purposed as a U.2 port connector. The [exposed] interface/port is exactly the same - it is the [underlying] controller/wiring that is different.) to SFF-8639 (This is new altogether, and is a replacement that is backwards compatible. The idea is to create a universal backplane that allows to support all known protocols. This end plugs into the hard disk's interface, not the motherboard) cable that additionally has a 15-pin SATA power receiver.

There are some implications here, namely that it is assumed you understand the technology as a whole. There are several ways you could connect that cable,

• The worst of the ways to do so would be to buy a M.2 NVME host [motherboard] interface to U.2 host interface adapter. The M.2 NVME host [motherboard] interface only provides 3.3v of power, and under this operation - depending on the drive you're connecting to the other end of the cable - you will need to plug a SATA power connector to the 15-pin SATA power receiver that is built into this cable.
• The other ways you can use this cable are through either a PCIe adapter that exposes a U.2 host interface (which provides enough power to ignore the SATA connector), or directly through a U.2 host [motherboard] interface built into the motherboard (which again, provides enough power).

Now, with that said - you've noticed that the end of the cable that plugs into the target drive's interface seems to align perfectly with a standard SATA drive interface (the interface on the target disk, not the host's [motherboard] SATA port). You are correct, and a standard SATA drive should have no problem accepting this connector - and it will indeed work. Even if you're using an adapter card that converts a M.2 NVME or M.2 SATA to standard SATA and the enclosure covers the SATA interface too narowly, you can shave it back using a dremel to allow the connector to fit.

All this mess is about power. A standard NGFF M.2 NVME and even NGFF M.2 SATA (the modern consumer-grade memory-stick style storage devices) leverage 3.3v of power. A normal 2.5" SATA drive leverages 12v of power. An enterprise grade U.2 drive (all that are available right now for between $400-$4k) can leverage both 3.3v and 12v and can consume up to 30w of power.

Many people want to leverage a U.2 connector and do so with a cable that converts a standard integrated M.2 host inteface (built-in to the motherboard) which only provides a 3.3v lane - and then want to connect a typical SATA drive that consumes 12v of power to it (they've run out of SATA ports, or just don't understand the better options here). This won't work without the extra power from a typical SATA power connector with the cable you're looking at. You won't need to worry, however, because the part of the cable that plugs into the target drive won't supply the 3.3v - that's in the gap you're noticing from the host M.2 interface. Also, because the host M.2 interface isn't supplying 12v of power to the cable (there's nothing connecting to those pins from the host M.2 interface) it is safe to plug a SATA power connector into the 15-pin SATA power receiver on the cable. However, if that U.2 side of the cable (double stack connector) is plugged into a PCI-E express to U.2 adapter, or directly into a host U.2 interface (built-in to the motherboard); you can do some serious damage plugging a 15-pin SATA power connector into the 15-pin SATA power receiver on that cable.

A U.2 interface allows to use 4 PCI-e lanes, and the option to leverage all 4 lanes as a single interface, or to choose to devidie the 4 lanes into two two-lane interfaces exists. This provides the option to leverage redundancy with NVMe storage protocol.

Where this becomes most applicable is in gaming, or in enterprise applications. You'll ideally use your host M.2 interfaces to install a NVMe storage device that's loaded with your OS of choice. You'll then ideally leverage the U.2 to gain the sheer performance gains possible with optional redundancy for gaming (install your game there for faster IO) or enterprise applications. It is entirely silly to use a standard SATA drive through a U.2 interface for most applications; though if you happen to have the gear, and wish to do it - it might not be so silly in the end if you're getting some sort of gain you're otherwise not getting while not losing anything because you have no other use for it.

I hope that helps to clarify this for anybody else looking to understand this that might end up here in the future.