MacPro 3,1 and NVMe SSD

evdberg

macrumors newbie
Original poster
Oct 15, 2018
18
0
I have Toshiba RC100 (2x PCIe 3.0) on a Icy Box PCIe adapter in my MacPro 3,1. In theory this would be able to run at 5Gbps on 2 lanes. However I get the following results:
Slot 2 (16x slot): 2.5Gbps, 2x (best performance, but right above the fan of my AMD7950)
Slot 3 and 4 (4x slots): 2.5Gbps, 1x

I have read a thread on this forum (that I can not find back) that this combo should run 5Gbps, 2x in slot 3 or 4. What am I doing wrong?

On the bright side, the MacPro does boot from this drive. And the BIOS finds this drive first, way faster than the SATA drives.
 

Ludacrisvp

macrumors 6502
May 14, 2008
334
121
99% of the threads about NVMe cards in the Mac Pro are on the 4,1 / 5,1 that have a better PCIe setup vs the 3,1.
I feel like you're probably seeing expected behavior in our older MP.
But maybe someone with more knowledge will sprinkle some insight here.

Make sure there is a heatsink on the NVMe card and maybe add a fan for it too?
If there is at least a heatsink on it, I wouldn't be too overly concerned about being near the GPU fan.
 

freqrider

macrumors member
Feb 10, 2019
41
7
Put it in slot 2. Slot 3 and 4 are pcie 1.1 x8 on cMP 3,1’s. Not sure if that adapter has a pcie switch? (chip) If not, you need to enable pcie II speeds with pciutils on slot 2. It’s cumbersome but I have a script to enable it at login. I’m getting 1500 MB/s with a cheapo Lycom DT-120 card and a 970 EVO in slot 2. If you have a blower style gpu, it won’t interfere with airflow.
 

evdberg

macrumors newbie
Original poster
Oct 15, 2018
18
0
@freqrider,
Thanks for your reply. No, the card does not have any switch on it. I looked at the pciutils, but that seems a bit complicated to get to run. Can you explain what to do?
 

freqrider

macrumors member
Feb 10, 2019
41
7
@freqrider,
Thanks for your reply. No, the card does not have any switch on it. I looked at the pciutils, but that seems a bit complicated to get to run. Can you explain what to do?
Here’s a zip with all you need. The two scripts I modified to auto execute and quit terminal are there, as are amended instructions. It was complicated at first but once I figured out the proper address, it worked great! Good luck.
[doublepost=1552867562][/doublepost]Being able to boot from it? Now that’s another story! ;) Think backing up your bootrom, extracting nvme.ffs DXE driver from latest 5,1 bootrom, injecting it into your bootrom with DXEInject and then flashing it back to your 3,1. Upgrading 5,1’s are child’s play compared to our machines. Sure is fun tho! ;)
 

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evdberg

macrumors newbie
Original poster
Oct 15, 2018
18
0
Thanks! I have booting from NVMe already working, the only problem is the speed ...