Finally there
A couple of screws by the processors' heatsinks were then removed and the northbridge's heatsink came away.
Almost there!
And here it is.
A look at the copper-clad bottom.
Here's the 120mm exhaust fan that pulls the air that's pushed by the two fans on the plastic duct, over the CPU and northbridge, and pushes it out of the back.
The cooling is quiet and effective, especially when considering that the CPUs/northbridge can have a combined TDP of around 350W.
A few flicks of the trusty screwdriver and the 'sinks come off, exposing the CPUs. The naked Mac Pro! Well, not quite, it still has a couple of E5462 Xeon CPUs.