Help with RX 470 Voltage Setting

[AVP]

Trying to dial in stable voltage settings for my Saphire RX 470 4GB (Non+) Hynix memory cards.

So far Claymore crashes after 4-16 hours, getting mostly "Temperature thread hangs" or occasional "GPU hangs" error message. My OC & Voltage settings are not out of the norm, I believe I've seen other forums/articles use similar settings and report stable results.

Here are my settings:
- In BIOS Timings flashed with 1500 straps
- In BIOS TDP increased from 85W to 115W & Max Power limit from 128W to 135W
- In BIOS GPU Core voltage changed from dynamic to static 850mv
- In Claymore: -cclock 1100 -mclock 2000 -cvddc 850 -mvddc 875
- Dual mining ETH + SIA using claymores latest v10.2
- Using AMD's BETA DAG Fix Drivers Released back in August v17.30.1029
- Windows 10, 4GB RAM, Virtual Memory set to 24GB

Observations:
- Changing -cvddc in Claymore does not effect GPU-Z VDDC values
- Only when changing -mvddc in Claymore, changes can be seen in GPU-Z VDDC

Questions:
- Is it not possible to change Memory Voltage for these cards, and changing -mvddc in Claymore actually changes Core Voltage instead of Memory Voltage?

- Or is GPU-Z not showing voltage properly? I'm assuming it displays Core Voltage, not Memory Voltage..

- What Core & Memory voltage settings should I be using to get stable results?

[alizali]

did you find any answer?
i have the same problem
-cvddc does not effect and voltage gpu-z shows

[AVP]

Ok, sort of a late response to my own question, but perhaps this will help someone.

Turns out in Polaris based cards (470/480/560/570/580) GPU core voltage will always be higher or equal to memory voltage. So even if cvddc is set to 850 but if mvddc is set to 900 both will be 900.

This has to do with how the core/memory voltages are derived from the board implementation.

[adaseb]

Is this a rig full of GPUs or is this just in your PC where you only have 1 GPU which is your main GPU?

Reason why is because if you got 1 GPU inside the 16x 3.0 slot, then it will run at x16 speed and  require more voltage than some GPU which is inside a x1 slot inside a USB riser.

So if you are getting this issue then you need to up the voltage a little bit because it will never be stable this way. Or just force it into x1 mode in your bios if its available.

[Zorg33]

I used to set my RX470s on 1000/800 core and 2050/850 memory

that results in the GPU setting being 1000/850.
Dont forget the Vddc >= Vddci rule

[AVP]

Whats confusing there are 3 voltages:

VDDC is the GPU core voltage.
MVDD is the memory voltage.
VDDCI is the I/O bus voltage (between memory and GPU core) and comes from the PCI-Express slot.

https://www.geeks3d.com/20101107/radeon-hd-6870-voltage-check-points-vddc-vddci-and-mvdd/

But yeah you can check that in GPU-Z unless it reports inaccurate settings..