I see. Is it possible to dual boot mac OS and Windows from those drives? The OP says the Sonnet doesn't support windows so I assume no. But what about the Accelsior? I don't have a boot screen because I'm using a Radeon Saphire Pulse RX580 video card. Any steps for installing both windows and mac on this drive when you don't have a boot screen?
How do you make a card that doesn't work in Windows? If a PC has UEFI and a UEFI NVMe driver, then it should just work. It should work in a Mac if it has new enough UEFI to boot Windows.
Without a boot screen, you need to be able to set the boot in macOS (use the bless command if Startup Disk preferences panel doesn't have the option). In Windows, the Boot Camp control panel may be useable, otherwise you can use the EasyUEFI app. I think there's a thread somewhere describing how to use Open Core to boot Windows "safely" using UEFI on old Mac. I think there's a thread somewhere describing how to get boot screen with rEFInd or Open Core (I'm not sure which or where - one can chain boot to the other). I haven't tried booting Windows with UEFI since my MacPro3,1 is too old for that - only Linux and macOS will boot properly using EFI on the Mac Pro3,1. I haven't tried getting a boot screen with a non-Mac GPU either.
Damn I already ordered this too. It says that it's mac supported and I do have two available sata slots in the HD bays. I'll see if it works before I try anything else. Maybe I'll get lucky.
It doesn't have a PCIe switch so you'll only get up to ~ 1500 MB/s. You'll need a cable to connect a SATA NVMe (but you don't have a SATA M.2, so nevermind). They come in various lengths. Some with one or two power connectors:
P22PM-15PF-7P-6IN
SATA 22 Pin Male to 7 Pin SATA Cable with 15 Pin SATA Female Power Cable
P22PM-15PF-7P-12IN
SATA 22 Pin Male to SATA 7 Pin and 15 Pin Female
P22PM-15PF-7P-18IN
SATA 22 Pin Male to SATA 7 Pin and 15 Pin Female
P22PM-P8-S18IN
SATA 22 Pin Male to SATA 7 Pin and 15 Pin Female - 18 and 8 Inches
P22PM-15PF-7P-1M
SATA 22 Pin Male to SATA 7 Pin and 15 Pin Female 1 Meter
P22PM-15-7-S3
SATA 22 Pin Male to SATA III 7 Pin and 15 Pin SATA Female - 12 Inches
P22PM-2X15PF-7P-2IN
SATA 22 Pin Male to SATA 7 Pin and 2 X 15 Pin SATA Female Connectors - 2"
P22PM-2X15PF-7P-6IN
SATA 22 Pin Male to SATA 7 Pin and 2 X 15 Pin SATA Female Connectors - 6"
Not sure I like the idea of that big ugly logic board floating around in my mac. Might as well just get an external m.2 enclosure instead of that. Can you boot mac and windows from an external enclosure?
It was kind of a joke because 400 MB/s (4 Gbps) max would be a waste for an NVMe)
External enclosure should be fine for EFI boot (not legacy BIOS boot which is what you usually use to boot Windows on old Macs - where Windows disk needs to be connected to one of the internal drive bays). NVMe requires PCIe.
External SATA (6 Gbps) might be the least expensive way.
No one has made a USB 3.x booter (10 Gbps) for classic Mac Pro yet.
Thunderbolt (22 Gbps PCIe) doesn't work well enough for booting a classic Mac Pro but I guess it's not impossible. It might take as much work as creating a USB 3.x booter.
External PCIe is super expensive (there's a subset of products at
B&H Photo - each manufacturer has their own website - I have the
Dynapower USA Netstor NA255A 16 lane host (64 Gbps) with PCIe 3.0 switch connected to my MacPro3,1), or you can make your own with a cheap single lane riser (4 Gbps) like the one I linked or you can get 4 lane (16 Gbps) cables at
ADT-Link. Only a product with a PCIe 3.0 switch with at least a 8 lane host adapter (32 Gbps) will give full performance from a PCIe 3.0 NVMe device (31.5 Gbps). There exist products with PCIe 4.0 switches - but I haven't seen anyone try that with an old Mac Pro yet - you would need an x16 host adapter (64 Gbps) to get full performance from a PCIe 4.0 NVMe device (63 Gbps) connected to a classic Mac Pro.
(Host bandwidth numbers assume Mac Pro PCIe 2.0 slot or PCIe 2.0 switch)