Problem: Sapphire Radeon RX580 Pulse 8GB

[rokmaver]

I update my OSx to 10.13.6 and install new GPU Sapphire Radeon RX580 Pulse 8GB, i have two questions:

1. Why DisplayPort doesn't work, HDMI and DVI works perfectly without any problem?
2. When system boot into high sierra, the gpu fans stop working immediately and after a few minutes graphics card produce some very annoying weird noise?

Do you have any ideas how to solve this problems, thank you for your help!

 

[trs96]

Try switching to the iMac 14,2 SMBIOS and then retest DP output.

 

[rokmaver]

Try switching to the iMac 14,2 SMBIOS and then retest DP output.

ok, DP works now like a charm... I also notice that FCPX has rendering issues with exporting H264, ProRes works fine... if I bench with Geekbench OpenCL right after booth I get around 145555, but if I test after 1 hour it drops to 44000... GPU fans are not working, works just one occasionally. Its also producing some weird sizzling noises, when I have connected three monitors to the RX580, my PSU is Corsair RM650X, is this enough power for this setup or is too weak?

 

[trs96]

8GB of Vram should be plenty to run 3 monitors even if they were all 4K monitors. I don't own an RX580 so I'm unable to test any of these things. Your RM650x PSU should be enough power for your system as well. The monitors plug into the wall so they are not drawing power from your PSU.

Try posting in some threads (User Builds) of other owners of the Sapphire RX580 and they should be able to direct you in ways to resolve the issues you're having. I would definitely want to be using the DP outputs that are enabled by iMac 14,2 sysdef.