MP 1,1-5,1 Solved: Mac Pro 2008 macOS 10.13 Slow SSD Speeds using PCIe

[nickds]

Solved: I had fitted the SATA card into a PCIe 1.0 instead of 2.0 slot - on the plus side I can confirm that the SEDNA card linked below does indeed work in a Mac Pro 2008 and the Mac can boot form it.

I have a Mac Pro 3,1 2008 with macOS 10.13.6 installed using dosdude patcher.

I have fitted a SEDNA PCIe x1 SATA 3 SSD adpater, link below, and to this have fitted a Crucial MX500 500GB SSD, link below.

In theory I now have a 6GB/s SATA 3 port with a 500GB SSD connected to it. I booted from a USB install media, wiped the SSD, and then installed macOS on it - it is funcitoning as the boot drive. I have enabled trim on the drive. The correct post install patches were installed.

When I run Blackmagic speed test I am getting speeds which seem more in keeping with SATA 2 around 180/190MB/s. Is there something I have missed? Should I not be seeing better performance out of this setup.

https://www.amazon.co.uk/Express-Adapter-Circuit-connector-included/dp/B0147BU80O
https://www.amazon.co.uk/Crucial-MX500-CT500MX500SSD1-NAND-Internal/dp/B0784SLQM6

Many thanks

 

[h9826790]

That speed looks very reasonable.

PCIe 1.0 x1 provide 250MB/s throughput.

Take 20% overhead away, real world max at about 200MB/s.

And now you can reach 195.2, which is ~98% of the max possible speed already.

 

[nickds]

That speed looks very reasonable.

PCIe 1.0 x1 provide 250MB/s throughput.

Take 20% overhead away, real world max at about 200MB/s.

And now you can reach 195.2, which is ~98% of the max possible speed already.

Thank you, your answer has pointed me in the correct direction and solved my problem. I was not aware that the 2008 Mac Pro had a mix of PCIe 1.0 and 2.0 so I put the SATA card as far away from the GPU to prevent heat.

I have moved the SATA card into slot 2 and the speeds are now what was expected!

I guess this can also act as a confirmation for anyone curious about this card that it does indeed work in a Mac Pro as a bootable drive.