Vostro 3470, M.2 SSD interface

The A1000 is B and M keyed aka its SATA. So its not going to work in a system that requires AHCI PCI-E M keyed only.

You must use something like the following  NVMe/M.2/PCIe 3  X4 SSD's

https://www.amazon.com/Samsung-PM981-Polaris-512GB-MZVLB512HAJQ-00000/dp/B07CZ42G6F

https://www.amazon.com/Samsung-PM961-Single-2280SS-Express/dp/B01N8Z82SY/

2KXJH 1TB Samsung PM981 22mm/80mm/2.38mm
66H10 1TB Samsung PM961 22mm/80mm/2.38mm
W53CK 1TB Samsung PM951 22mm/80mm/3.73mm
68V6F 512GB Samsung PM961 22mm/80mm/2.38mm
3WF8W 512GB Samsung PM951 22mm/80mm/2.38mm
M7DVX 256GB Samsung PM981 22mm/80mm/2.38mm
3YC83 256GB Samsung PM961 22mm/80mm/2.38mm

RDHKG 1TB Toshiba XG3N 22mm/80mm/3.73mm
R1DHH 1TB Toshiba XG5 22mm/80mm/2.23mm
NPFCP 1TB Toshiba XG4 22mm/80mm/3.73mm
70KCW 512GB Toshiba XG5 22mm/80mm/2.38mm
7VPP2 512GB Toshiba XG4 22mm/80mm/2.38mm
CC1D0 256GB Toshiba XG5 22mm/80mm/2.38mm
8D5HT 256GB Toshiba XG4 22mm/80mm/2.38mm

X10G4 1TB Hynix PC401 22mm/80mm/2.15mm
D8DTJ 1TB Hynix PC300 22mm/80mm/2.38mm
0WYP0 512GB Hynix PC300 22mm/80mm/2.38mm
R2RPG 256GB Hynix PC401 22mm/80mm/2.15mm
XHFF7 256GB Hynix PC300 22mm/80mm/2.38mm

YR3K3 1TB Liteon CX2A 22mm/80mm/3.73mm
2345G 512GB Liteon CX2A 22mm/80mm/2.38mm
XVRV7 256GB Liteon CX2A 22mm/80mm/2.38mm

94XPK 512GB Sandisk A400 22mm/80mm/2.38mm
Y2HHR 256GB Sandisk A400 22mm/80mm/2.38mm

A1000 is an NVMe product per the manufacturer.  Keying is really not a reliable way to tell.

https://www.kingston.com/us/ssd/consumer/SA1000M8

Does it not show in the BIOS at all?

An "x2" SSD should work in an "x4" slot.  If you have the latest motherboard BIOS then I would guess either a bad SSD or a bad motherboard.  FYI the Mushkin Pilot is just slightly more expensive and works perfectly in a Vostro 3670 which is very similar.

B keyed M2 is SATA not pci-e. The kingston isnt going to work. pins 11 - 21 ARE required for PCI-E vs SATA operation. An M.2 SSD module is designed only for either a SATA or PCIe interface, not both at the same time.

B KEY IS NOT pci-e AHCI

Sigh, there's so much confusion regarding M.2 SSDs...

Generally, M.2 SSDs come in two flavors:  NVMe and SATA.

If your machine has a M.2 SSD slot first question I'd ask is what does it support - NVMe or SATA (or both)?

Per Dell's manual/specs:

• Vostro 3470, M.2 SSD:  SATA
• Vostro 3670, M.2 SSD:  NVMe

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If you want a SATA M.2 SSD in the Vostro 3470, you're good to go with something like Samsung's 860 EVO/PRO (which note comes in M.2, 2.5" and mSATA formats).  The M.2 slot should be capable of SATA III's 550 Mb/s performance for large sequential files.

Alternatively, if you really want a NVMe SSD in the Vostro 3470 you can add a M.2 NVMe to PCIe adapter to the Vostro's PCIe x16 slot.  This has been demonstrated to work here.  Of course, you can not have both a discrete graphics card and NVMe SSD, since they both require the x16 slot.  With the M.2 adapter, the Vostro 3470 should be capable of NVMe's 3500 Mb/s performance for large sequential files.

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On the other hand, with the Vostro 3670 you can use its built-in M.2 SSD slot for a NVMe SSD, like Samsung's 970 EVO/PRO or Mushkin's Enhanced Pilot.  The M.2 slot should be capable of the SSD's max performance for large sequential files, up to around 3500 Mb/s, since the slot is PCIe 3.0 x 4.

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NVMe SSDs with less PCIe channels, like the Kingston A1000's PCIe 3.0 x 2, will work fine in a x4 slot, they'll just use only 2 channels (and have half the performance that the M.2 slot is capable of).  Yes, the A1000 is a NVMe M.2 SSD.

Note for all the above SSDs, small file 4k performance is about the same.  Due to this you may see little actual performance difference between them for many usage scenarios.  But, an upgrade from a spinning hard drive to any SSD is a much, much larger increase in drive performance.