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Old 06-17-07, 07:30 PM   #21
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Join Date: Jun 2007
Posts: 3
Talking Re: Geforece Go 7600 fan problem

shaundennie, thanks! All I needed was one more nudge in the right direction. After having worked on this on and off for 4 months, I can't tell you how sweet success is.

I've actually gotten somewhat comfortable monkeying around in the ACPI scripting language...of course, it helps to have a copy of the appropriate spec too. See:

Btw, you shouldn't have to worry about nuking your machine when swapping out the DSDT under Linux... Of course, you may cause yourself some issues when booting a bad DSDT, so I recommend having multiple initrd images that you can select from your grub boot menu. Then you don't have to fly without a safety net.

After diffing your original ASL against my changes and notes, I saw what you were talking about re: VTMP, and decided to give my DSDT a (w)hack or two.

I observed a few things (keep in mind this is Satellite P100 BIOS v3.5):

1) You can make the "static" value change to VTMP in either the _REG() method or in the NVIF() method and get the same results... a fan that is constantly on and a GPU at about 47 Celsius. Nice.

2) Changes to VTMP in the WSBC() method seem to make no difference. This makes sense, however, because this method belongs to the AMW0 namespace (a device with PNP ID PNP0C14). This is apparently a WMI device which of course only matters under Windows.

3) Based on my testing so far, it appears that the value of VTMP is inversely proportional to fan speed. This doesn't really make sense to me, as I thought it would be just the opposite. Perhaps VTMP doesn't mean "current video temperature". Anyway, I tried cranking it up from 3C to 41 and then to 46 (thinking this would mean 60 Celsius, 65 Celsius and then 70 Celsius), however the fan actually runs slower as the value increases. With VTMP at 3C, the fan runs at a nice medium speed and does a sufficient job at keeping things cool.

4) It would be wonderful to have a user-mode program under Linux to control the value in VTMP. With the right documentation, I'd be happy to write one in C. If anyone has suggestions or experience in this area, let me know.

I have attached both the original ASL and my latest hack which includes my changes to make the GPU fan, sound card and other devices to function. Hopefully it will prove useful to others.

Thanks again for your reply. It made me look in just the right place!

-Justin P. Linenkohl
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