weird clock on 15 750

[mozartripper]

hello i have some strange clock (problems) with my i5 750
when idle as show on the screenshot below the core speed is 3.2 ghz and multiplier 24

and under a "medium load" the core is 2.8ghz and multiplier 21

does anyone have an idea of what might cause this ?

specs : mobo/cpu/ram : dell studio xps 8100
video card and psu have been replaced with better ones

 

[munkle]

Do you have the newest version of cpu-z?

Edit: judging by bottom screen shot you do.