Undervolt Vega 64 using 17.10.2

allen5055

[H]ard|Gawd
Joined
Mar 25, 2012
Messages
1,553
I just installed the 17.10.2 driver for my Vega 64 x 2 and R9 290 system. It does have the DAG performance of the blockchain driver and I can easily get the same 44Mhash per card. I can also undervolt... to a point.

With the blockchain driver voltage control was lacking, yet applying a registry tweak and using OverdriveNT allowed me to achieve 44Mhash at 0.8125 vcore and 130w power draw.

I can't get my vcore down that far with the new drivers. The lowest I can go is 0.92v. I've tried fiddling around with the core clock, leaving the voltage on auto, changing the power limit, changing the voltage to manual and putting the core voltage and memory voltage at various combinations. I've tried core/memory voltage combos of 850/800, 800/800, 800/850, 950/900, 900/950, etc. Nothing works. OverdriveNT does not work. Applying the registry tweak makes my computer not boot into windows.

If I leave the voltage on auto and decrease the power limit to -45 and the core to 1000mhz, I can get to 0.92vcore. I can also get to 0.92 vcore by lowering the voltage manually and then applying a -45 power limit.

Any ideas on how to get to lower voltage with the new drivers? I'd really love to be on the latest driver chain again so I can play games too.
 
good to know the new 17.10.2 drivers have integrated the DAG performance fix.

sorry I don't have the answer for the rest of it. I'll be watching though. the most I ever got out of my Vega 56 was about 37MH/s. I didn't try overdrive NT though - i'm not familiar with it. something else to look up.
 
With overdriventool I was able to get the vcore down to 0.875v which helps but it's still not the same as 0.8125v. I estimate that I'm still 30watts over where I could be per card.

That being said, the new drivers let me overclock my HBM far more, I maxed out at 1220 but it's not stable. I'm stability testing now. at 1220 HBM memory speed I get 48.5mhash/card!!!!!
 
For sake of something $800ish to compare $475 Vega56 to:
My 12GB Titan X Pascal gives only 39.5Mh at maximum memory overclock (+1000 in XOC) and not entirely stable.
Thats 384bit GDDR5x 11Gbps. Even this hashrate assumes viewing my desktop through another card, else -1.5Mh.
I have not yet measured the Watts, but at 65% power and 100% fan, it still blows heat like a small hairdrier.
Voltage bouncing up and down in the average vicinity of 0.8V. Sometimes dips as low as 0.75V...

OTOH with $475, I could buy a trio of 1050ti's and bank $70. Needing two extra risers, So maybe only $55 saved.
Hashing 45Mh near the comfortable edge of stability (Micron). Maybe much as 46.5Mh with luck and Samsung.
I have measured (average of Qty 8) at 60W per card, would be something like 180W for a Vega comparable trio.
Spreading the heat challenge across three sinks definately helps, even without heatpipes.

FYI, Etherium (Ethash) is not Vega's strongest coin. Vega profits highest mining Monero XMR (CryptoNight).
Etherium is also not TitanXPascal's best coin. Favoring ZCash (Equihash) or VertCoin (Lyra2REv2).

And we shouldn't forget a pair of RX570 also fit Vega's budget, 44-60Mh (Ethash) depending memory and bios.
Course you are then going to spend for a more capable supply, extra cooling, and the inevitable electric bill.
 
Last edited:
I succeeded in applying a 0.82v undervolt for ether mining.

I figured out how to create a custom powerplay table registry mod to undervolt with the new 17.10.2 drivers. Basically, through much trial and error, I found that changing the GPU P clock speeds makes them fail to be registered, which is why this registry mod no longer works with the new drivers. I was able to use Halfasar's compiler to edit Hellm's powerplay registry table and modify the GPU P-state voltages. If I put P1-P7 at 850mv, that equates to a GPU vcore of 0.8313v. If I put P1-P7 at 840mv, that equates to a GPU vcore of 0.8215v. For some reason I also have to put my GPU clock using OverdriveNTool to the same clockspeed for P6 and P7 for this to work. The downside is my HBM doesn't seem to go above 1100 stably with the undervolt, although eventually I may figure out how to overcome that. I'm going to tweak it more, but I'm heading out for the weekend and can't afford to have it crash while I'm gone. http://www.overclock.net/t/1633446/preliminary-view-of-amd-vega-bios
 
Back
Top