PCIe SSD questions - NVMe, AHCI, SATA ...

[Jdebunqe]

I'm finding M.2 PCIe SSD cards for Mac Pro 5,1 to be very confusing. I'm looking for cheap, not super-fast. I'd like to boot from SSD.

This is what I think I know:

AHCI M.2 - M-type key - works fine in Mac Pro tower without drivers using any 3rd party M.2 to PCIe card. Bootable. Older tech, rather expensive and harder to find.

NVMe M.2 - M-type key - will work but have to install special kernel module. Can't boot. Likely to break with OS upgrade. But relatively cheap and abundant. (Q: Why does 'about this Mac' show NVMExpress under Hardware if you need to install a hacked kernel module?)

SATA M.2 - B+M key - Q: Is there any way to make this work in a Mac Pro? Using just the PCIe slot, or do I need a cable? These B+M key units seem to be cheap as surplus and leftovers from upgrades.

I could imagine booting from an old 128GB SSD in the drive bays, and having another NVMe SSD for user data, but the fact that OS upgrades will be messed up bothers me.

 

[h9826790]

If you are looking for cheap and not super fast bootable natively supported SSD, no need to touch the PCIe slots (and better not to). Just plug in a large enough SATA (e.g. 1TB 850Evo) into the optical bay, then you are good to go.

The M.2 SATA SSD still SATA SSD, apart from more expensive, more trouble (require adaptor), there is no real benefit, because the speed still limit to SATA speed.

If you want all sequential speed from a SATA SSD, then a PCIe SATA 3 card will do, not necessary with cable. e.g. Sonnet Tempo SSD is one of the choice. It's bootable as well. However, by considering the adaptor is relatively expensive. And it will occupy a PCIe slot anyway. I will go for the Kingston HyperX Predator PCIe AHCI SSD, which is not that expensive, come with the adaptor, and also bootable.

I personally will avoid NVMe. Yes, it's fast, however, as you said, Apple may break it on any OS update. And since you said you don't need very fast SSD. It's not worth to take the risk.

 

[Jdebunqe]

If you are looking for cheap and not super fast bootable natively supported SSD, no need to touch the PCIe slots (and better not to). Just plug in a large enough SATA (e.g. 1TB 850Evo) into the optical bay, then you are good to go. ...

Yeah, I'm thinking of doing this. On the other hand, there are sometimes good deals on big, lightly used NVMe disks on ebay. In terms of bang for buck, I think that NVMe would win, if it worked. And used M.2 SATA are cheap too.

 

[kschendel]

I imagine this is obvious, but for the benefit of any newbies reading this ... you can plug just about any SATA SSD (ordinary SATA, not m.2) into a drive bay and it will work just fine (and is bootable). Since the cMP is SATA 2, drive bay SSD's are limited by the 3 gbit/sec SATA 2 speed and there is in general no point to spending extra on a super duper high speed SSD, pretty much anything will work and beat the pants off of spinning rust.

 

[kohlson]

You can try and sort through a PCIe card set up with an M.2, and get faster disk performance. But you have to do your homework. The easy/reliable/painless method is as has been suggested here: duct tape a SATA2 or better 2.5-inch drive into the other optical drive slot (I did). Been a workhorse for years, now.

 

[DPUser]

When using the optical bay for SSDs, I recommend moving the optical drive from the upper to the lower bay, then using it as an SSD shelf. If you don't move your Mac around, you don't even need to fasten the SSD; just rest it on the optical drive. Double-sided foam tape will do the job if movement is anticipated.