PM G5 tower: Video drops out when picture too bright

[gsteemso]

I have a Power Mac G5 tower (model ID PowerMac7,3) with a Radeon 9600 XT video card. Whenever the room is not uncomfortably cold, if the video signal it puts out is above a certain average brightness, that signal cuts out unpredictably, as often as every couple of seconds in the worst case. On a hot day it becomes quite unusable. I infer that some component has become marginal with age, such that a high enough average value of the video signal causes it to overheat. (I suspect a dried-up capacitor, but without any real knowledge of the component-level design of the card I'm guessing blindly there.) Interestingly, this also happened with another card of the same model that I accidentally bought on eBay, even though it had never happened to me at all before this year.

Has anyone else experienced this, and if so, what did you do about it?

 

[Byrd]

The Radeon 9x00 (9700 and 9800 mostly) are highly prone to over heating and/or the card can flex over time resulting in dry joints sometimes in the layers of the PCB itself or under the GPU core. I'd try to gently flex the card during use (wear gloves!) to see if you can elicit any change.

Are you using the same LCD every time - have you checked that too on other computers?

What happens when you point a fan at the GPU, does it turn off still?