Core clock speed in CPUZ different from specifications

[KuJaX]

I am testing a few video cards for some general use systems for family. I couldn't help but notice some strange numbers from CPUZ.

The core clock specified on the video card is not the same as what CPUZ says it is running at. See the chart below

(Explain: CHIP is the Graphics GPU, SPEC CORE is what the specifications says it runs at and CPUZ CORE is what CPUZ says it is running at.

CHIP | SPEC CORE | CPUZ CORE
4650 | 600 | 300
4350 | 600 | 110 (WTF)
3650 | 600 | 300

I am a bit confused on how this all works. Why would they all show a specified core of 600, yet none of them actually say 600. I could understand 300 for the 4650 and 3650 incase it is because all three cards have two outputs, but where in the world does 110 from the 4350 come into play?

With graphics cards, is one significantly better off going with a higher model GPU, regardless of GPU core clock speed?

 

[SicKlown42012]

Idle speeds. These cards downclock when there isn't a load on them to save power and lower temperatures.

 

[KuJaX]

If it is indeed idle to save power, is there a way to disable it? How would I know for sure it is from some idle feature?

 

[SicKlown42012]

Run a game in windowed mode. It will then goto full speed, if that is what's doing this. The only way to completely disable it, that I know of, is to download MSI Afterburner(1.4 or before) and edit the config to enable a unofficial overclocking method, which keeps the gpu at full speed and voltage all the time.