5 ms·

Many people are undervolting them, which brings power draw down considerably and leads to only a miniscule difference in performance.

shmerl 9y ago
So why are they so overvolted by default?
- sangnoir 9y ago
  It's a design decision, which boils down to AMD loves to "overclock" by default to squeeze out as much performance as possible. I could easily imagine the mirror-universe version of this conversation had they done otherwise "You can gain 5% perf by 'overvolting' AMD GPUS. Why don't they do this by default?"
- paulmd 9y ago
  Unpopular truth: because that's where they need to be to ensure stability and yields. There is a wide variation in the stability of hardware across various different tasks. An overclock/undervolt that is stable in one task is not necessarily stable in others, as anyone who's overclocked can attest. f.ex Just Cause 3 needed several hundred MHz less than I could get in TF2 or Witcher 3. The voltage is set where it needs to be to ensure that there's no instability in any program, on any sample in a batch. People look at one task and one sample and assume that their OC must be stable on everything, on every card in the batch. In reality it's not, or not to the degree that the manufacturer requires. Yes, you can get extra performance on any given sample by eating up your safety margin and pushing closer to the limit of that specific sample's frequency/voltage curve. But as the economists say: if there were free money laying on the sidewalk, AMD would have picked it up already. They're not stupid, they ship the voltages they need.
  - shmerl 9y ago
    > They're not stupid, they ship the voltages they need. That's my point then. Vega just needs too much by default. Hopefully next iteration will be less power hungry.
paulmd 9y ago
Let's not pretend like this is unique to AMD though: NVIDIA products can be undervolted too. And if you are willing to drop 10-15% performance, you can cut power down by 40-50% on Pascal, just like Vega. The same voltage-vs-frequency curve applies to both products.

shmerl 9y ago

So why are they so overvolted by default?

sangnoir 9y ago
It's a design decision, which boils down to AMD loves to "overclock" by default to squeeze out as much performance as possible. I could easily imagine the mirror-universe version of this conversation had they done otherwise "You can gain 5% perf by 'overvolting' AMD GPUS. Why don't they do this by default?"
paulmd 9y ago
Unpopular truth: because that's where they need to be to ensure stability and yields. There is a wide variation in the stability of hardware across various different tasks. An overclock/undervolt that is stable in one task is not necessarily stable in others, as anyone who's overclocked can attest. f.ex Just Cause 3 needed several hundred MHz less than I could get in TF2 or Witcher 3. The voltage is set where it needs to be to ensure that there's no instability in any program, on any sample in a batch. People look at one task and one sample and assume that their OC must be stable on everything, on every card in the batch. In reality it's not, or not to the degree that the manufacturer requires. Yes, you can get extra performance on any given sample by eating up your safety margin and pushing closer to the limit of that specific sample's frequency/voltage curve. But as the economists say: if there were free money laying on the sidewalk, AMD would have picked it up already. They're not stupid, they ship the voltages they need.
- shmerl 9y ago
  > They're not stupid, they ship the voltages they need. That's my point then. Vega just needs too much by default. Hopefully next iteration will be less power hungry.

paulmd 9y ago

Let's not pretend like this is unique to AMD though: NVIDIA products can be undervolted too. And if you are willing to drop 10-15% performance, you can cut power down by 40-50% on Pascal, just like Vega. The same voltage-vs-frequency curve applies to both products.