oc problem of E6400

[MegaTonTNT]

hello yesterday i tried to overclock my E6400 on a gigabyte motherboard GA-EP43-DS3 (rev.1). Using windows 7.

i reach with the stock cooler of intel @3.10Ghz but the windows (Computer -> properties) can read only 2.67Ghz.

the program cpu z read every change i did. Is that problem of the windows?

 

ps: can someone tell me a good water cooling for my cpu?

 

thanks