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The RX Vega 64 Owners Thread

What you see as 'memory voltage' in WattMan maybe VDDCI. That was what it was on Polaris, I know some OCN members that measured it via DMM. Polaris memory had dumb controller for VRAM with no data interface, so SW/VBIOS could not set voltage.

VDDCI on Fiji had a dumb control on PCB with no data interface, so SW/VBIOS couldn't change it's voltage. Fiji did have HBM voltage controlled by IR3567B so as it had data interface VBIOS mod allowed voltage change. No official or 3rd party app although allowed access.

As VEGA is seeming so close to Fiji, I reckon HBM voltage can be controlled via VBIOS/SW. Would AMD give access I don't think so. The numbers in Wattman just do not match known DMM readings and VBIOS info.
 
Figured I would put the card in one of my mining rigs today for a bit to see what it's performance was like, as expected it was poor (same power consumption as five RX560s and half the performance). But something interesting I noticed which I really wasn't expecting, is that when configured with a custom fan curve so it doesn't throttle under load, and placed in the same machine as a reference GTX1080 also configured with a custom fan curve to prevent throttling under load, the V64 is actually quieter. Obviously it's producing more heat and this can be felt at the back, but the better cooler means it's pumping it out quicker, and yet it's not as loud because while the whine of the GTX1080's fan drowns out it's airflow, the V64's airflow drowns out it's fan and is MUCH less annoying if you're in the same room as it.

TLDR: A Vega 64 reference sounds less annoying under load than a GTX1080 reference.
 
Got a waterblock on my 64 now; HBM certainly seems to be quicker from just being cooler (someone on reddit was talking about some form of thermal throttling), it also still seems to get hotter than the core most of the time - which would make sense if it's at 1.35V!
 
TonyTurbo78 said:
Ok makes sense. One thing im not getting though. If HWinfo is displaying things vice versa, that the 1.356v that's being displayed in HWinfo is actually the memory voltage. My question as above is, how is there that much voltage going to memort when in Wattman it's only set to 1050mv?
Click to expand...
Not sure on that one, I'll try to find out.
 
AMDMatt said:
Not sure on that one, I'll try to find out.
Click to expand...

ok cool. Just trying to understand the voltage situation here as best as can be with the buggy software reporting. And regarding the default memory voltage, why is it set to 1050mv on my card where as the AIO versions and the 56 seems to default at 950mv? Shall I drop mine down from 1050mv to 950mv?
 
TonyTurbo78 said:
ok cool. Just trying to understand the voltage situation here as best as can be with the buggy software reporting. And regarding the default memory voltage, why is it set to 1050mv on my card where as the AIO versions and the 56 seems to default at 950mv? Shall I drop mine down from 1050mv to 950mv?
Click to expand...
I would leave HBM voltage at default settings and focus on core voltage for now.
 
AMDMatt said:
I would leave HBM voltage at default settings and focus on core voltage for now.
Click to expand...

ok will do.

And one last things, appreciate all your replies. If the HBM is plodding along at 1050mhz, then half way through the bench stress test it drops to 800mz and won't bounce back to 1050mhz, what causes that? It can't be throttling off temps because my core and memory temp max at full load are only 36c and 38c respectively. Is that a voltage thing, not enough juice?
 
TonyTurbo78 said:
ok will do.

And one last things, appreciate all your replies. If the HBM is plodding along at 1050mhz, then half way through the bench stress test it drops to 800mz and won't bounce back to 1050mhz, what causes that? It can't be throttling off temps because my core and memory temp max at full load are only 36c and 38c respectively. Is that a voltage thing, not enough juice?
Click to expand...
Sounds like a bug i reported recently, wait for a driver update to fix it. I found adjusting HBM voltage was a sure fire way to trigger it.
 
TonyTurbo78 said:
ok will do.

And one last things, appreciate all your replies. If the HBM is plodding along at 1050mhz, then half way through the bench stress test it drops to 800mz and won't bounce back to 1050mhz, what causes that? It can't be throttling off temps because my core and memory temp max at full load are only 36c and 38c respectively. Is that a voltage thing, not enough juice?
Click to expand...

Does it do the same if you overclock it slightly less?
 
Nemesis.ie said:
@TonyT - are you on GPU-Z beta? The latest version has a "Hot spot" function, it might be interesting to see what that is showing (we don't know where the sensor actually is yet) when you see the throttling.
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I'm on 2.2.0, don't see any hotspot function so I guess there might be a newer version.

AMDMatt said:
Sounds like a bug i reported recently, wait for a driver update to fix it. I found adjusting HBM voltage was a sure fire way to trigger it.
Click to expand...

Ah ok, will just see how it goes for now then. Might just drop it to 1000mhz and wait for next driver. The good news is, I've benched the core at 1750mhz @ 1100mv and only hit 39c so I know the core is good for it. Memory will go to 1100mhz when the core clock isn't so aggressively overclocked.

Kaapstad said:
Does it do the same if you overclock it slightly less?
Click to expand...

Kinda, it does and it doesn't, just trying to get my head around it really. I can bench for 30 minutes with the HBM at 1100mhz (when the core clock isn't overclocked through the roof) and it doesn't happen. But If I raise the core to 1700mhz and above, that's when the HBM drops to 800mhz at times and just will not revert back to it's speed, same if I drop the memory to 1050mhz with an aggressively high core overclock. To me, it feels like I either overclock one or the other to the limit, it doesn't seem to like it when I try being aggressive with both core and memory.
 
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