I'll let you Google for MBM5, it's easy to find.
I had to lookup your CPU coolers:
To compare, the GlacialTech lgloo 2320 that Pritorian uses is an all Aluminium unit.
See this PDF.
So maybe your temps aren't off by much after all.
You shouldn't risk slipping those probes there, unless you feel confident. The die rises 0.80 to 0.88 mm above the substrate.
You would do better by sticking it on one of those HSF fins.