No Fan Spin on Gigabyte RX570 + Sonnet Breakaway Box - iMac14,2 (TB1) 10.14.6
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No Fan Spin on Gigabyte RX570 + Sonnet Breakaway Box - iMac14,2 (TB1) 10.14.6  


Active Member
Joined: 4 years ago

I have a Gigabyte RX570 Gaming 4G (GV-RX570GAMING-4GD) in a Sonnet BB 550W connected to a 27" iMac (Late 2013) and its fans never spin in Mojave 10.14.6.

I thought it might have been because its thermal management was programmed to be on the quiet side in the bios or something and the temps reported by IOReg were ~50°C but while I was adding an AIC to use my Thunderbolt Display I realized that the card was hot enough to fry an egg on it.

Also something I didn't notice till now, this particular card has a "Fan Stop" indication led that turns on when the fans stop, and this light is not on... Is there any way to make the fans work? Even manually setting the speed would be enough for me, I'm a bit lost now since even the temps don't seem to be monitored properly.

Does anyone know how to fix this at all or have any pointers for troubleshooting steps I could take? I think it's a driver(controller kext) issue since it works fine in a pc. I'm about to try in boot camp now, but having some trouble, this iMac has iGPU frame buffers decoupled with a Nvidia dGPU. I'll try getting Mojave on an Xserve and seeing if it does anything different if I just can't get boot camp to work...

Edit: I forgot to mention this iMac is missing its internal display, I don't think that matters has anything to do with this problem but just in case....

This topic was modified 2 years ago

2018 Mac mini I7 - Sonnet BB550W + Gigabyte RX570 4GB - Alpine Ridge AIC – (TB3 to TB adapter) – Apple Thunderbolt Display
2019 15" MBP i9 also works as expected in above setup
2012 15" rMBP works with purge-wrangler
All on 10.14.6 (18G84/b) for debug kernel...
iMac14,2, no Built-in LCD, GT 755M dGPU - Bricked after Catalina DP update tried to flash nonexistent T2 chip. Mucking around with Pomona clip, looking for BootROM dump if anyone has one 🙁

Founder Admin
Joined: 5 years ago

Have you tested to make sure this RX 570 is working properly in a desktop setup? Your observations so far indicate the GPU is faulty. If you bought it used, my recommendation is to flash the original vBIOS on it to make sure it works the way it should.

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