[SOLVED] Increasing power limit to a vega 56

[alexalexa]

Hi guys, I heard that in some cases increasing the power limit in your gpu increases performance. On Google it says that there is no harm in increasing the power limit however I increased it at +20% and the fans are blasting at around 98% compared to 75% when the power limit was set to 0. Is this normal or should I just keep the limit at its default settings?
{I tested this in FurMark}

 

[tennis2]

"Power Limit" allows the GPU to apply additional voltage (and hence additional wattage) to achieve higher clockspeeds along the stock voltage curve. More watts = more heat = faster fan speed to dissipate that heat.

Download GPUz for an easy way to see what frequencies, voltages, temps, fan speeds are occurring under various circumstances.

In AMD Performance Settings you can set it to "manual" and enable "advanced tuning" to expose the 7 (?) performance states that are being used. You can then enter lower voltages for various frequencies. This will result in a more "efficient" power curve than the stock/auto settings.

You can also try enabling "Chill" if you have a variable refresh rate monitor, or Frame Rate Target Control [FRTC] if you have a fixed refresh rate monitor. Both of those features allow the GPU to downclock itself if it's able to output more than the set amount of FPS for the particular game you're playing, hence saving power/heat/noise.

From another thread: (Vega56, Sapphire reference blower)
Factory stock settings (the baseline):
BIOS1, default 'Balanced' profile - 800MHz HBM2/Auto voltage/Auto clock/Auto temps
Performance = 72.9fps = 100%
Avg. clock = 1387MHz = 100%
Avg. fan = 2315RPM = 100%
Avg. Watts = 175W = 100%
Avg. VDDC = 952mv = 100%

AMD's idea of an efficient BIOS profile:
BIOS2, 'Power Save' profile - 800MHz HBM2/Auto voltage/Auto clock/Auto temps
Performance = 69.9fps = 96%
Avg. clock = 1278MHz = 92%
Avg. fan = 1885RPM = 81%
Avg. Watts = 135W = 77%
Avg. VDDC = 900mv = 95%

The lowest I can go:
Custom profile - 940MHz HBM2/867mv/1402MHz core/75-80C
Performance = 75.8fps = 104%
Avg. clock = 1296MHz = 94%
Avg. fan = 1888RPM = 81%
Avg. Watts = 133W = 76%
Avg. VDDC = 868mv = 91%

In summary, I don't seem to have much control over the undervolt, or the resulting core speeds. If you don't want to use the BIOS2 'Power Save' profile, your best bet for tuning Vega is to do what I did, without the trial-and-error:

1. Find out what the minimum HBM2 voltage is (by dropping it to something stupidly low like 700mv, and then recording the actual minimum voltage)
2. Set that voltage for 'State 6', 'State 7', and 'Memory Voltage'
3. See how high you can push the HBM2 clocks before corruption
4. Dial it back a few percent for stability
5. Set power limit to +50% because you don't want that interfering with clockspeeds
6. (Optional) Monitor the average fan speeds at full load, and then set the target speed to 15% higher, and minimum speed to 15% lower.

This last step keeps the cooling more constant and avoids the noisy spikes in fan noise that happen when the default fan settings let the temps climb too high, resulting in a fan-control 'panic' burst that's well in excess of your target speed.

I'm a little underwhelmed, really. The 'Power Save' profile on BIOS2 is almost as low as the card can operate already, and most of the performance gains from Vega appear to be in the HBM2 overclocking, which (hopefully) anyone with a Vega card already knows. Still, with a bit of tweaking I managed to get a 4% performance boost over stock settings whilst using 24% less power