At what point does the
CPU become unstable from high temperature? I have Athlon XP 1600+ AGOIA Y only doing 1.7GHz stable @ 1.80V, but my load temps rise to 65C

At 1.85V I am almost at 70C. There is something really wrong with my watercooling? I could be getting better temps on air.

Could my temps limit my
CPU, coz I've seen almost every AGOIA Y hit 1.8GHz easily. What's wrong with mine? Any ideas?
My waterblock uses 1mm base plate and is a simple maze. Pump is rated at 212 gph paired up with a large heatercore with 2 120mm fans. My water has the room temp, which is about 21C. Only thing I can think of is that the base plate is to thin for the low gph pump like mine. Or maybe my waterblock design is somehow faulty.
Please help me guys.