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Stuck VDDC and HBM clock on RX Vega 56

Question asked by deadman3000 on Sep 12, 2017
Latest reply on Nov 5, 2017 by vsav

I need some help. My RX Vega 56 has problems with the VDDC and memory clock getting stuck after using multiple monitors and after using any 3D apps. The only way to reset it is to set the secondary and tirtiary monitors to disconnected (hotkey set to C:\Windows\System32\DisplaySwitch.exe /INTERNAL is the quickest method) and reboot Windows 10. Not only that but the VDDC keeps changing and getting stuck higher than it should when idle. The default VDDC is 0.750mV and 167Mhz HBM in single monitor mode. In multi monitor mode HBM stays at 500Mhz until boosted in a 3D app. But the VDDC gets stuck in various states from 0.7688 up to 1.1mV after exiting a 3D app when idle! This causes a constant power draw on my system (Tested with wall wart) whereby my usual powerdraw is ~90w but stuck at 1.1mV it draws a constant ~120w. Rebooting or turning off the PC and clearing the capacitors sometimes bring it down to around 0.8375. But only setting to single monitor then a reboot brings it back down to the lowest VDDC. I don't expect it to be as low when multiple monitors are connected obviously but I do expect the powerdraw when idle to remain stable.


BTW sometimes in multi monitor mode HBM will drop to 167Mhz after running a 3D app. Which is odd in and of itself.