I have a Core 2 Duo E7200 on an ASUS P5Q-Deluxe MOBO. I have upgraded both the chipsets and BIOS to the latest one per ASUS Support. No matter what I do I can not get it to run at native speed of 2.53 HGHZ. When I run CPU-Z it show it switching between 1603mhz and 2533mhz. In addition the multiplier changes from 6 to 9.5. All my settings in BIOS are on auto. I am not trying to overclock. Any suggestions would be helpful.
Sounds like your power management is working correctly!
newer processors have the ability to down clock into low power modes to same $$$ when max speed is not needeed and will clock up when it is required.
If you want to spend more on your power bill and lock it in to high speed, you should be able to find the setting under power management. Options are balanced (default), preformance (max speed all times) power saving (min speed)