Yeah, those temp graphs are WAY too hot for stock speed. Yes, you're getting below optimal flowrates, but that doesn't even begin to explain those kind of temps.

Again, I used to run an Exos-2 setup (same pump/rad/fans), with two blocks in the system. And even at 3.6 GHz/1.425 Vcore, my Q6600 temps peaked at about 63-64 degrees under OCCT, with the fans set at five. Which is why I'm almost positive that you've got a CPU --> waterblock heat transfer problem.

So... not to beat the topic to death, but the number one suspect in such a case is the thermal compound.

I'd just swap over to some Koolance fluid next chance you get. It isn't the best, but it isn't the worst either, and shouldn't give you any problems.