Reported tempurature appears to be incorrect

[Dave Suffling]

Binary package hint: nvclock

Using an Asus-branded nVidia EN8400GS (PCI-E), the GPU tempuratures reported by lm-sensors and nvclock differ substantially. For example, lm-sensors reports 64 degrees C, while nvclock reports 38 degrees C. Touching the heatsync on this fanless card suggests that the value reported by lm-sensors is likely to be correct.

System details:

System is a Core 2 Quad Q6600 with an Asus P5QL-E motherboard. The EN8400GS is attached via PCI-E.

lspci(8) reports the graphics card to be:
01:00.0 VGA compatible controller: nVidia Corporation Device 06e4 (rev a1)

Installed graphics driver is nvidia-glx-177 (177.70-0ubuntu2).
Installed NVClock self-reports v0.8 (Beta3). Package version is 0.8b3-1ubuntu1.

[Wallo013 (walloo13)]

This bug has been reported a long time ago to nvclock dev, but no new release is available since this time.
Here is the patch for src/backend/nv50.c:

    139a140,146
    >
    > //Temperature support for G92
    > if(( (nv_card->bios->device_id&0xff00) == 0x600)||( (nv_card->bios->device_id&0xff00) == 0x610))
    > {
    > temp = nv_card->PMC[0x20008/4]&0x3fff;
    > return (-13115 + temp) / 18.7 + 1;
    > }

You can find more information about this patch, including a .deb for 8.04 which works with 8.10 too for quick test, here:
http://computersstoneage.blogspot.com/2008/06/asus-nvidia-8800-gt-gpu-temperature.html

This solution is accurate for my Asus 8800GT and is based on the formula used by Asus, which is used by Rivatuner too.