XP90 temps normal on overclocking?

[Kantana28]

Ok ambient temp is 21C, using XP90 with arctic silver 5 and a Delta 92mm 69CFM fan. All this is cooling an Intel 650 overclocked to 247x17=4201 and loaded 100% with 2 x Prime 95, temps rise and remain constant at 59C.
Is this the limit of air cooling? Any hopes of improvements with XP120 and bigger fan?

 

[bjc112]

247x17=4201

4.2Ghz?

What voltage?'

I would impressed with 59C and 4ghz.

 

[Kantana28]

Stable at 1.4375 VCore. To get 4300MHz need to raise VCore to 1.475V but then when running 2 x Prime 95 the temp reached throttling...
I can get much higher speeds but need extra VCore and the XP90 is not doing it for me. What kind of temps are others getting when overclocking their Intel 5xxJ and 6xx CPUs? The throttling temp is not a constant and will happen between 59 and 61C depending on the VCore used.