Why can't most software tell me my correct CPU speed?



I have a i7-3820 @ 4.75Ghz (x38*125) and it is infact at 4.75Ghz according to CPU-Z but, that is just about one of the only programs that tells me the right speed. Task manager thinks its at 3.75Ghz and just about every other program thinks it is 4.5Ghz. I've checked with CPU-z I know its not a huge issue but, It would be great if I could fix it.

My PC if anyone cares to take a look. http://www.userbenchmark.com/UserRun/1466715


Task manager is notorious for telling the wrong thing - normally it shows spec or spec with turbo boost, other progams can do same or even over inflate what it is at. Some take readings at intervals (as the CPU is often changing speeds depending on the load it's under, so while frustrating, yes you often will see a variety of 'speeds' it is suppose to be running at. Like you. I prefer CPU-Z

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