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Has anyone here purchased or know someone who has purchased the Radeon 5770 for use in a Mac Pro 1,1? I recently put one in my Pro and starting experiencing fan issues right from the start.

Under periods of GPU stress like games and such, the fans will start revving in a random pulsing manner. There's no rhyme or reason to the fan pulsing, which can turn on in short bursts or longer stretches of a few seconds except that it always seems to rev to the maximum fan speed and it only occurs when the heat on the GPU goes above a certain temp (around 97F+).

If there is anyone who might have advice or experience with this, I'd appreciate it before I go to fight with Apple Care.

Thanks!

Edit: I've done some testing with cooling the case to keep case temps down below 80F and have discovered that the fan pulsing happens regardless of how cool the case is, leaving me to posit that my problem has nothing to do with case or GPU heat but something more insidious.