Question 1

Does the nvme m.2 ssd to pcie x16/x8/x4 card support 4.0 speeds, or 3.0 only?

Accepted Answer

Everyone is falling over themselves to give you the wrong answer. Two of these comments are referring to the hero vii and not the hero viii which the dark hero OP has is based on.

His board has 3 x16 slots, the top 2 to the CPU can either be configured for a single slot at 16 lanes, or x8 on both. The CPU only has 24 lanes total, and 4 go to the chipset 4 to the m.2 slot1.

Chipset works like a switch providing 16 more lanes are higher latency 
The 3rd slot is x4 wired pcie 4.0 to the chipset.

So yes, he should be capable of 4.0 speeds if this adapter supported it. That he can't suggests he either used too many of the 16 lanes his chipset provides or this card can't provide 4.0 passthrough.

Question 2

In re: to the sabrent nvme m.2 ssd to pcie x16/x8/x4 card with aluminum heat sink. why does paperwork that comes with the card says for x16 slot only?

Accepted Answer

The physical form factor is for a 16x "slot" with the retaining tab/clip. This should provide adequate physical support since it does not use a bracket for the card slot. Depending on the mainboard/motherboard, Installing it in an 8x or 4x slot connector may not align properly or provide sufficient support.  Not all physical 16x slots are actually wired to support sixteen (16) PCIe lanes.  The same is true of smaller slots.  To get the full performance, the slot must support or be "wired" for at least four (4) logical lanes.  For instance I have it installed in a physical 16x slot that is only "wired" for four (4) lanes, which in this case happens to be the perfectly matched scenario.

Question 3

Does this device require pcie lane bifurcation on the motherboard, or is it handled on the card itself?

Accepted Answer

That is handled by the card itself. It has an ASMedia PCIe switch built in for broad compatibility.

Question 4

With all slots populated, do the drives run at pcie 3.0 x1 speeds?

Accepted Answer

Each drive can be independently accessed with up to PCIe 3.0 x2 lanes per M.2 slot.

ASIN	B084GDY2PW
Best Sellers Rank	#21,557 in Computers ( See Top 100 in Computers ) #315 in Hard Drive Accessories
Brand	SABRENT
Built-In Media	NVMeM. 2 SSD To PCIe x16/x8/x4 Card
Color	M.2 PCIe Card + Heatsink
Compatible Devices	Desktop
Connector Type	PCIe x16
Customer Reviews	4.5 4.5 out of 5 stars (5,834)
Finish	Aluminum
Global Trade Identification Number	00840025214163
Item Dimensions	10.2 x 5.1 x 1.3 centimeters
Item Weight	80 Grams
Manufacturer	SABRENT
Mfr Part Number	Sabrent
Model Number	EC-PCIE
Nominal Power	12 Watts
Number of Items	1
Number of Ports	4
Package Quantity	1
Power Plug Type	No Plug
Smart Home Compatibility	Not Smart Home Compatible
Specific Uses For Product	Improving computer storage
UPC	840025214163
Unit Count	1 Count

Sabrent NVMe M.2 SSD to PCIe X16/X8/X4 Card with aluminum heat sink (EC-PCIE)

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