[C++] Changing the FSB

[.Yoss.]

So I've seen programs like SetFSB being able to change the fsb from their software but I've not been able to find out how or where they get the data from.

I've read some odd thread where they say that it can only be achieved by writing to the correct memory addresses, well I know how to write to memory but how do I find what I have to edit? Is there anywhere I can learn more about these "PLL"'s and mem addresses I have to find and where to search for them?

O.S: Windows

 

[jMerliN]

You'll need to do this from a driver, as I don't know any windows API that lets you do such things. And it'll most likely involve invoking the BIOS to do the changes for you.

There may also be a chipset API from the motherboard manufacturer that lets applications do this from usermode.

 

[EliteGM]

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[.Yoss.]

You'll need to do this from a driver, as I don't know any windows API that lets you do such things. And it'll most likely involve invoking the BIOS to do the changes for you.

There may also be a chipset API from the motherboard manufacturer that lets applications do this from usermode.

Never done anything in ring0 before or drivers, but it sounds like a nice challenge. Btw, I'm going to do this on an old laptop so if anything goes wrong it won't be too painful, but using the laptop also means that there's probably no apps or support from the motherboard manufacturer so I guess the only thing I can try to do is invoke the bios, I hope it is possible to invoke it even if it's a laptop (you can't change anything regarding to the voltage & clock of any of the components, including the FSB from the bios here). But I guess it is though, or setFSB wouldn't have been able to do anything about it either..

Correct me if wrong though, I know little about drivers at this point in time.

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I didn't know they released some of the code , however they have released the unessential part to the public and hidden the interesting details in a dll. I don't mind reading asm but I just hope it isn't packed by some crazy packer.