MP 1,1-5,1 NVMe card linking at 2.5GT in slot 3 on Mac Pro 5,1

[Rubycon22000]

Hi,
I’ve a genuine Mac Pro 5,1 running mojave updated to the latest 144 firmware and booting from a sata ssd drive. I also have an nvme drive in slot 3 (in a x4 pcie slot adaptor), but it only links at 2.5GT/s, not the 5.0GT/s the 144 is supposed to enable. I know it’s not the card as it connects at 5GT/s in slot 2 (and 1). The os isn’t misreporting the link either as speed test on the drive shows 750mbs transfer in slot 3, and 1500mbs in slot 2.
Any ideas? I thought the 138 (and subsequent) firmwares enabled 5GT/s on all slots?
Why not just use slot 2 you might ask? I’ve recently upgraded my gfx to a rx580 and annoyingly, it is 2 1/2 slots wide, not 2.
Steve

 

[tsialex]

Hi,
I’ve a genuine Mac Pro 5,1 running mojave updated to the latest 144 firmware and booting from a sata ssd drive. I also have an nvme drive in slot 3 (in a x4 pcie slot adaptor), but it only links at 2.5GT/s, not the 5.0GT/s the 144 is supposed to enable. I know it’s not the card as it connects at 5GT/s in slot 2 (and 1). The os isn’t misreporting the link either as speed test on the drive shows 750mbs transfer in slot 3, and 1500mbs in slot 2.
Any ideas?

It's a WD blade or a PCIe v4.0 blade that is incompatible with PCIe v2.0 switches? This is a known issue.

Did you checked the adapter with slot 4 to eliminate the slot itself?

I thought the 138 (and subsequent) firmwares enabled 5GT/s on all slots?

You misunderstood the issue, it's not the way you think.

Before 138.0.0.0.0 Mac Pro firmware only configured 5GT/s for Apple made PCIe cards. Since 138.0.0.0.0, all PCIe v2.0/v3.0 cards are initialized at boot time to 5GT/s.

 

[Rubycon22000]

It’s a WD sn770, which is PCIe v4, but it’s not plugged into a switch card, it’s a single blade pci x4 adaptor card.

Yes I checked slots 3 and 4 link at 2.5GT and 1 and 2 link at 5.0GT.

 

[tsialex]

It’s a WD sn770, which is PCIe v4,

Why you bought a known incompatible blade?

PCIe SSDs - NVMe & AHCI

This is a general info thread for blade SSDs that can be used in the Mac Pro. This is a WikiPost so anyone with the proper credentials may edit it. NVMe SSDs can be used as a boot drive in the MP5,1 and MP6,1 with the latest firmware installed (beginning with version 140.0.0.0.0 for MP5,1 and...

forums.macrumors.com

but it’s not plugged into a switch card, it’s a single blade pci x4 adaptor card.

Yes I checked slots 3 and 4 link at 2.5GT and 1 and 2 link at 5.0GT.

PCIe 3 and 4 share 4 lines from the south bridge via an IDT PCIe switch. So, its the old known issue with WD blades, replace it with another manufacturer.

 

[Rubycon22000]

I had a cMP 3,1 before this one and put it in slot 2 so it was fine, I got a 5,1 and it was fine in slot 2 as well, but now my gfx card is thicker I’ve had to move it up a slot into 3 and discovered this issue. I’ll either live with it or move the gfx up one and use slot 1. I’m not going to get another blade as I already changed it from a 970 evo which I was having TRIM issues with (long boot times).
But I really appreciate the explanation. At least I can stop trying to solve an unsolvable problem (with the blade). 😊

 

[tsialex]

Not a good idea, since the SN770 is know to cause KPs when in heavy load.

It's a no go blade for a MacPro5,1.

 

[Rubycon22000]

Not a good idea, since the SN770 is know to cause KPs when in heavy load.

It's a no go blade for a MacPro5,1.

KPs?

 

[tsialex]

KPs?

Kernel Panics.

 

[borgo1971]

Not a good idea, since the SN770 is know to cause KPs when in heavy load.

It's a no go blade for a MacPro5,1.

Oh, ****... ! Even this (after problematic Samsung SSD)?! Maybe I got a KP just yesterday, while I didn't use the MacPro. I just heard it rebooting. I can't understand why I didn't see this thread before I bought it... even I lurked about SN770+MacPro before. What NVMe SSD (2TB) can you recommend for the cMP?

 

[sfalatko]

Oh, ****... ! Even this (after problematic Samsung SSD)?! Maybe I got a KP just yesterday, while I didn't use the MacPro. I just heard it rebooting. I can't understand why I didn't see this thread before I bought it... even I lurked about SN770+MacPro before. What NVMe SSD (2TB) can you recommend for the cMP?

Take a look here -

PCIe SSDs - NVMe & AHCI

This is a general info thread for blade SSDs that can be used in the Mac Pro. This is a WikiPost so anyone with the proper credentials may edit it. NVMe SSDs can be used as a boot drive in the MP5,1 and MP6,1 with the latest firmware installed (beginning with version 140.0.0.0.0 for MP5,1 and...

forums.macrumors.com

 

[John Fu]

here is my info

 

[xlambchopsx]

here is my info

View attachment 2325886

How are you possibly getting 8 GT/s in a 4x slot with MacPro5,1?

 

[tsialex]

How are you possibly getting 8 GT/s in a 4x slot with MacPro5,1?

PCIe switched adapter, SysInfo shows the downstream of the PCIe v3.0 x4 adapter, not the real slot speed (because of the PCIe switch).

 

[borgo1971]

I've a strange (at least for me) behavior with my cMacPro (flashed with tsialex reconstructed firmware, but I guess it won't match). I discoverd that my Crucial P1 nvme SSD, that I resumed after many issues with Samsung 970evo plus and WD770, and I used for a while some years ago (it was my first nvme SSD) with no problems, now performs much worse as aspected. After many tries, I found that it links at x4 2.5GT/s if I put it in slot 2, and x2 5GT/s in slot 3. This limits throughput to about 700/750 GB/sec (measured with Blackmagic disk speed test), although I am sure at the time I bought it the disk was running twice as fast. Putting the drive with the same adapter, in a PCIe slot in a hackintosh, the speed is as expected, which is about 1500GB/sec, and the connection results in 2x 8GT/s.
Can someone explain this behavior? P1 has a new installed version of Monterey 12.7.3, with entry EFI folder copied from WD770 (OC 0.97). And even with some problems, both the Samsung 970EVO and the WD SN770 (in the same adapter I using now with P1) were running at x4 5GT/s in slot 2 from my MacPro, with a throughput of about 1500GB/sec.
P.S. I also verified with the Crucial utility that the drive is in excellent health.

 

[John Fu]

PCIe switched adapter, SysInfo shows the downstream of the PCIe v3.0 x4 adapter, not the real slot speed (because of the PCIe switch).

please let us know how to test it for real speed, I checked the SSD speed, and it is about 2000M

 

[tsialex]

please let us know how to test it for real speed, I checked the SSD speed, and it is about 2000M

The PCIe link speed is always 5GT/s for a MacPro5,1 after 138.0.0.0.0, seems you didn't fully comprehend what I've wrote.