cpu clock too low / force cpu clock / overclock I have a MacBook from a few years back. 
When I use it write some code and browse the internet, the fans go very fast and the noise is horrible. But the temp shows only 70 C.

So I used SMC to force the fans to 3000rpm. I really don't mind frying my MacBook as long as its quiet.
Now instead of the temp rising to 90 C or more (what I want!), my MacBook decides to lower the cpu clock to 0.8 Ghz. And it becomes completely useless. I can't even use one program at a time.
Even the mouse cursor lags.

What can I do? Can I force the CPU clock? 

Model: A1286 i7 2.0 Ghz (High Sierra) Early 2011

edit: i don't even want a turbo boost or anything (would be nice). i just want to use the 2 Ghz and not only 0.8 Ghz.
That sounds most probably like an old Mac, which will not go very fast anyway these days. 

But the symptoms really can describe a few things of underlying problems.


misconfiguration: look at the programs installed and delete what's unneeded, especially background applications (make a clean install ot the OS if all else fails)
SMC settings got confused: perform an SMC-reset
aging hardware: the thermal grease could be bad by now and might need replacement (try the other options first)
being dirty: if the grills for the fans are clogged (most probable here) just open the case, clean it out.