I have a Compaq Pentium III 1.3 GHz Intel processor and D815 motherboard. When it starts up, it displays a Compaq logo with its clock speed (i.e. 1.3 GHz) and also it displays on BIOS the processor rated as Compaq Intel 1300 MHZ.
Problem is that it doesn't display this speed on "My Computer" properties, nor on "dxdiag". Instead it displays Intel Pentium III ~660 MHz. In some places it also shows x86 Family 6 Model 8 Stepping 6 Genuineintel ~664 MHz.
The BIOS (according to dxdiag) is 686P0 v1.16.
Also my computer doesn't work like it has 1.3 GHz processor.
Why it is so?
Has it got something to with overclocking?
As far as I know these processors support SpeedStep(EIST) and other power saving features, and it looks like something its enabled because the multiplier is dropped. To test if thats the case put it under heavy load(with prime95 or something like that) and then run CPU-Z.
Anyway, look in bios for stuff like C1 state or AutoHalt, or StopGrant