You understood the problem completely backwards. It's the high power draw at the startup that triggers the racing fan bug. Btw, the GPU fan rotation has nothing to do it and it's not only GPUs that can cause it. Even fan less cards like some NVMe switched cards or some SDI ones can trigger it. It's the power draw from the PCIe slot that triggers the PCIe fan ramp up at the startup. Another thing, it's a common problem of SMC 1.39f5 (early-2009) and it's not so common with 1.39f11 (mid-2010/mid-2012) Mac Pros.Yeah, I know this behavior exists with genuine Mac cards as well. There's a thread somewhere on this forum that goes in to great detail about the cause of this behavior, and I think the key difference was that the original HD5870 starts spinning up fast at boot (and draws more current) while the GTX680, for instance, starts in low power mode.
So, maybe, if there's a metal card that does boot in "high consumption mode" (or something) it would get rid of this behavior...?
I was just hoping someone here would have first hand experience with such a card. I know it might seem strange obsessing over this instead of just accepting the software workaround. But I can't help it, when something's not working the way it's supposed to I just can't relax. ? And then I'd rather stick with an older OS version.
(Actually, I'm one of those who'd love to stick with Snow Leopard, if only it was more widely supported. Every OS update since then has introduced new ways of handling things that require me to change how I work, which I don't like. Duplicate instead of Save as, showing MP3 tag titles instead of filenames in spotlight search, replacing ftp with sftp, making "natural scrolling" the default . Although, I really enjoy iCloud drive, and auto-save can be nice sometimes, though sometimes it can be bad.)
If you have two displays connected to an AMD GPU, AMD GPUs with two or more displays draw much more power than NVIDIA GPUs with two or more displays, it's almost certain that you will trigger it, while with NVIDIA GPUs only some high end cards like TITAN have it. Mojave and newer macOS releases usage of METAL since the driver startup makes this undesirable behaviour more apparent then with High Sierra or earlier macOS releases - more power draw, more chances of triggering it.
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