Finally got the chipset/PCIe stable at BCLK206

The signal-tweaks with -92, -16 and -31 on the rest of them (except PCIe signal 1 & 2 = default) did the trick, and both chipset and PCIe is stable now. CB 11.5 is not scoring 27+ any longer, and 3D-applications are running fine too.

I've tried a few minutes Prime-smallFFT with vCore=1.20(load) and it didn't crash either , but I'm going to test the core-stability with overnight Blender 3D-render.
The core may need one (or tow) notches more vCore to get stable, but chipset/PCIe-stability has been the limiting factor for BCLK201+ so far.
Still testing, but so far so good.

2 x X5650 @3.91GHz 1.20v, VVT=1.34v, IOH=1.375v, (all load)