Further Testing with GeForce 7600GS
In an attempt to replicate the error, I went to the nearest computer shop and bought another GeForce graphics card knowing full well that it might and probably will die - being a mainstream shop, the highest-end card they stocked was a GeForce 7600GS, so we picked up one straight away. This was a Leadtek card that used no fan, just a heat sink with heat pipe design.
We installed the card without any cooling but the GPU got so hot before Vista even had a chance to load, that the system shut down. This suggests that some of the recent GeForce cards do come with thermal diodes and do have thermal management effectively working. Keep in mind though, that was out of Windows Vista - we're talking around the BIOS POST screen area!
We could have tried removing the heat sink while in Windows Vista but we weren't on a mission to get electric zaps, so we didn't attempt it. The chances are high that the same thing would have occurred - the graphics card would have kept running until it got so hot that the GPU core fizzled out and died, hopefully before we saw fire. Keep in mind that electrical fires are the hardest to control, especially without a fire extinguisher - I will be buying one soon, for safety sakes.
Industry Concerns on the subject
We were very interested to hear ATI's thoughts on the subject and asked them over email what would happen if cooling failed on a Radeon based graphics card under Windows Vista - we had a Power Color Radeon X800GTO spare and ready for death in our Taiwan lab.
ATI suggested that emulating a failed cooling system was not advisable but as long as the particular graphics card partner installed thermal control, their driver should be able to handle the rest without any problems under Vista. Since we could not confirm if Power Color used thermal control, we didn't attempt the test on ATI's advice. From the ATI driver team in Canada:
If there is no thermal controller, then the chip can be damaged (as there is no way to monitor the board - it is up to each partner whether they include a thermal chip - some leave it off to save money on the cost of the board).
But in the case of the X800 GTO (it may be that a thermal controller was included on the board, but OD is still not supported) - I don't know, but I would not recommend taking the heatsink off of your board - there's a good reason why they're there
So this isn't a driver issue - the board needs the thermal Asic to begin with, if one is there it is very easy to monitor the temperature and ensure nothing happens to it.
Our concern with this response is that ATI / AMD doesn't force their graphics board partners to install a thermal monitoring device on Radeon graphics cards. Both nVidia and ATI should make the thermal monitoring a must have device on all graphics cards from low-end to high-end, as all graphics cards get hot.
If you are the unlucky one who buys a graphics card with no thermal monitoring (since the card partner wanted to save a few bucks!), you want to pray you don't have any cooling failure. It's high time ATI and nVidia and other graphics cards companies force their partners to implement thermal control - don't make it an option!
The saving of just a few dollars does add up when you start considering how many graphics cards are sold but this should in no way come at cost of lessened safety - we are working with electronics and moving parts and they do fail from time to time without reason.
We will no doubt quiz ATI and nVidia more about this and also talk to board partners about the issue.