SOLVED via 'Pisla's Mod"
It doesn't appear as difficult as it looked at first glance:
It consists of using simple taps on 8 long wires, which are routed from the DVD area through the HDD shelf, to the GPU. I'll post any extra details or pictures after I do it ... as I'm sure I"ll find areas...
My 4,1 / 2009 unmodified dual proc Mac Pro was having intermittent crashes (every *other* boot, it would randomly freeze). I took the CPU tray out and discovered a wiggly northbridge heatsink that needed to be refastened to the board. Taking off CPU-A to get to it, I noticed the thermal paste...
So, I was thinking of upgrading my early 2009 Mac Pro 4,1 Nehalem dual Quad-Core 2.26GHz to a Westmere 12-core but before getting my hands on such CPUs I thought I’d try out a couple of x5570 2.93GHz quad-cores (lidded, fitted with washers and 5mm thermal strips, I happened to have laying...