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 Post subject: Questions and info on Cool ‘n’ Quiet
PostPosted: Thu Aug 05, 2004 6:23 pm 
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How does Cool ‘n’ Quiet interact with non standard BIOS changes to voltage and multiplier? I’ve been reading up on the subject but I’m still not clear on this topic. I can see why any changes that have been made by Clockgen will be lost once CnQ does its thing. That makes sense as they are simply state changes and not stored anywhere.
However BIOS settings are different. Does CnQ revert to the BIOS settings for voltage and multiplier once it shifts to the Max P-state? It seems unlikely, as it will have to determine any other intermediate settings, where they exist, from another source.
Using a user configured BIOS setting would potentially lead to the problem of the max P-state utilising a lower clock speed than the highest intermediary state.

Does anyone know how CnQ determines which settings to use for its various states? I guess it’s either in the CPU’s microcode or in the driver itself. If it’s the later, then that opens up the possibility of tweaking the values. Probably not for Windows, but the Linux driver source code is available for alteration.

I find it strange that AMD have chosen not to use an intermediate state of less than 1.8 GHz, even for the 2.0 GHz part. Does anyone know why this is? Logically it seems to make more sense to spread the states more evenly between the 1 GHz base frequency (CG stepping) and the max frequency. I suppose they profiled this and came up with their solution.

Note:
The Pentium M version of Speedstep uses up to 8 different states, which are very linearly spaced by frequency and voltage.
Also it uses software to change states, this is opposed to previous implementations where the GHI# pin is used to toggle between two states.

Has anyone written a utility to monitor CPU load and launch Clockgen in ghost mode, with appropriate settings as demanded? This way you could have an extendable and custom replacement for CnQ, which would be more flexible. The programming would be easy enough, I just don’t know if Clockgen would load and execute quickly enough to make this feasible. Any thoughts on this? I fancy a crack at this myself and I could also implement an intermediary P-state or two more to my liking :)

Do all motherboards only support CnQ with 1 memory stick?

The Aopen AK89 Max does support CnQ, according to a post by a company employee on the support section of their website. I think you need a later version BIOS though and the option seems to be hidden away in an obscure section of it.
Aopen don’t mention support for CnQ on their website or user manuals for any of the boards that are known to support it following my research. Don’t always assume the worst.

As a silence lover, I’m excited by CnQ in a way that no mainstream CPU technology for the desktop has hit me before. It seems to have come out of the trap half limping, but if you check your facts thoroughly, you should get a good result. I’m still researching which board to purchase, but can’t wait to try it out.

SC


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