Colin on 25 May, 2018 05:05 PM
Thanks for reaching out to us about this. Geekbench 4's Multi-Core CPU scores are not expected to scale linearly with the number of cores in a device, as core scheduling, inter-core communication, and cache behaviour can have a substantial effect on the device's measured performance.
I'm not able to find specifications for the Mac Pro 2009 with a 12-core X5670 -- is this the Mac Pro 2010, or am I perhaps looking in the wrong place? The average Multi-Core CPU score for the Mac Pro 2010 with a 12-core X5670 (available here) is similar to to your result, if that is the case.