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Old 06-23-2019, 11:56 PM
Darryl Ramm Darryl Ramm is offline
Join Date: Nov 2010
Location: USA
Posts: 13,427
Default Re: Upgrading a Mac Pro 5.1 12core 2.4Ghz

Originally Posted by skizzo View Post
PCIe NVMe SSD's booting SLOWER than SATA SSD's on cMP models are quite well documented and discussed.

PCIe is external hardware, SATA is internal. Priorities are placed on internal connections for obvious reasons. Putting more cards into PCIe slots is going to slow the boot process for having to scan and load more crap. I don't know the intricate reasons to why PCIe NVMe SSDs boot slower but they just do.....for 4,1 and 5,1 cMPs. That is what we are discussing here. If your implying your surprised because it's different on a PC then that is irrelevant. It seems like they do boot faster on a PC but again, we are talking about a 10 year Mac Pro, not the 10 month old z390 chipset MB's that boot in 10 seconds with a NVMe SSD.
You got stuff backwards on internal/external as others have pointed out. You are likely being confused by extra labels that macOS/Finder ads to "external" drives, that's largely just a convince about how they are treated by the Finder. That has nothing to do with their performance.

The reasons that booting cheesegraters in some configurations is not that NVMe SSDs are slow or on slow connections, it's because of the complex POST and boot process in the cheesegraters. The "other reasons" I referred to. And if you are having slow boot there you have to look at this. The answer is not "they just do", the answer is very specific reasons.

One of the better resources (but may be a bit hard go find with a search) is.

There are also several large threads on Apple support forums and macRumors etc. including this one is a great resource: (note the sy to use PCIe switch enabled PCIe adapter cards to run a 4 lane x PCIe 3 NVMe SSD at full PCIe 3 speed in a cheesegrater which is only PCIe 2... does that buy aggregating 8 PCIe 2 lanes).

With all these threads folks have to be careful about old information, many still say NVMe wont' officially boot on a cheesegrater, etc. It did not until Mojave and Boot ROM 14.0.0... NVMe boot was not officially supported on the cheesegrater, latest Boot ROM is I believe 14.5. And you sure do not want to be trying to hack or patch this Boot ROM like may have been needed in the past.

The cheesegrater upgradeability with these recent changes is amazing. I'm sad I don't have a cheesegrater any more. I'm all in on MacBook Pro, and I am using an external Samsung X5 NVMe Thunderbolt 3 drive or things including alternate boot images. Pretty stunning portable drives.

Last edited by Darryl Ramm; 06-24-2019 at 12:09 AM.
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