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macrumors 68000
Original poster
Jan 12, 2014
I bought this little and cheap PCI Express to Express Card 34 adapter, and installed it in my Mac Pro 4,1: It supports PCI Express 2.0 and link speed up to 5 Gb/s. I did not connect the supplemental internal USB3 cable, because the Mac Pro has no connection for this. However, it is not needed.

It worked out of the box with the Sonnet Tempo Edge SATA Pro 6 Gb ExpressCard The speed connected to a Crucial M4 was 224 Mb/s Write and 371.7 Mb/s Read. Better than with my Caldigit fasta-6gu3 PCI-Card.

I also tried the Express Card 34 adapter with a PE4L-PCI-Adapter and a NVIDIA GTX 570 as external GPU.

The external GTX 570 was recognized without any problems and run out of the box (additionally to my internal GTX 680). Reportet PCI Link speed was 2.5 GT/s.

There was no performance increase on OpenGL with the second GPU. Unigine Haven gave me a score of 1341. But on OpenCL it showed almost the double performance: Luxmark 2.1 reported a result of 1414 instead of 771 with the internal GPU only.

Maybe this could be useful for GPGPU…


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Last edited:


macrumors regular
Jun 14, 2016
I think the PCI Express to Express Card 34 adapter card brings alot of possibilities. Unfortunately the Delock PCI Express card to Express Card 34 that Synchro3 is using is not available anymore.
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