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Comment by marcofatica | Hacker News Reader

What does the equivalent EPYC consume?

>Single-socket submissions show that AMD's 128-core, 256-thread Epyc 9754 scores right around 922 in the benchmark, about 2.58x higher than Ampere's top-specced Altra, the M128-30, which comes in at 356.

>While a clear win for AMD's Bergamo, it doesn't take into consideration other elements like power consumption. AMD's part is rated for 360W and can be configured up to 400W, while Ampere's has a TDP of just 182W. So yes, it may be 2.5x times faster, but it potentially uses 2-2.2x more power.

that's still a major win for AMD. 2x performance per core means you need half as many servers (which is way cheaper) and all your latency bound operations happen twice as quickly. (also I'm pretty sure you can underclock the AMD system to the point where it's the same power and 50% more performance)

At a certain density, though, power budgets come into consideration.

For 2 or 4 sockets per RU, you could be dealing with hundreds of kW per rack, and the heat that entails.

For certain deployments that could make sense. For others, a lower power, but still high core count solution could be better.

You can always solve power density by not fully populating a rack or underclocking or both. If Epyc is better it's better; it doesn't depend on density.

It's definitely better for certain workloads.

I would assume that undervolting and underclocking will likely drop that power consumption quite considerably.

> For others, a lower power, but still high core count solution could be better.

I think OP's point is that you'd need over twice the number of the lower density cores to get the same performance, thus by going that route you'd end up needing more power to get the same computational resources.

To put it simply, with ARM you'd need a 4U to get almost the same compute as a 2U of AMD.

Let’s round that to 200 watts difference. At 20c per kWh that’s an opex difference of about $1 per day.

Public cloud providers will sell you that amount of compute for about $50-$100 per day.

The lower end of that is the Ampere processor and the high end would be the AMD 128-core processor.

In other words, they can make $49 more by using the AMD CPU per day.

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