I am experiencing si ilar situation.
At stock speed my Q6600 G0 SLACR can run OCCT from 36c to 57c (21c range)
BUT
If I run my Q6600 G0 SLACR at 3.0Ghz runs OCCT from 43c to 70c+ (27c range+)
All stock voltages , common sense stuff turned off in BIOS
Asus P5Q -E , Scythe Ninja Rev...