[magila]

Calling this "Unexpected" seems like a bit of a stretch. In particular this part:

> Of course, in the server space, we've known for a long time that maximum efficiency occurs with a high number of cores running at lower frequencies, and that efficiency trumps performance on machines with high core counts. But I never considered that the consumer Ryzen CPUs could also benefit from the same thing until now.

makes no sense. This principal applies to all CPUs from the smallest SoCs to the largest server CPUs, why on Earth would you not expect it to apply to desktop CPUs?

You could do the same thing with a 6 core i7 and 2133 memory. Intel CPUs have long supported an adjustable power limit to constrain operating frequency based on power consumption just like he describes for Ryzen.

[ceratopisan]

You are confusing principle with implementation. Reducing clock speed reduces power usage and you can compensate with more cores is indeed a truth. However, finding that option in consumer hardware has been relatively difficult. That is the surprise indicated.

[magila]

Ryzen is known to be memory constrained even with much faster memory than he used. It is completely predicable that he found his CPU to be severely starved for memory bandwidth thus enabling him to reduce operating frequency without penalty.

This is like putting an LS engine in an otherwise stock Miata and acting surprised that you can run the engine at lower RPM and still put in good lap times.

[AstralStorm]

Are you kidding me? That's only true if the constraint can be removed in a hardware upgrade. Apparently latter day Xeons are not much better at hiding memory latencies than Zen and no longer outrun it as much like they did Bulldozer on other operations which made the latencies irrelevant.

In other words, he's reached peak CPU. As in a faster unit will not speed it up, and more cores can only do that to a point. Amdahl law (power efficiency variant) and also memory controllers say hello.

[BeeOnRope]

Note that the author is not claiming that he compensated with more cores. He is claiming that the performance is roughly the same, at the same core count (8), regardless of frequency.

[BeeOnRope]

Well I suppose the part that might not apply to desktop parts is "efficiency trumps performance". Many desktop uses don't care about efficiency, but care about performance.

For servers, the purchasing decisions are probably much more quantitative, and if you are buying a high core count machine it probably means you have a parallelizable workload, so no efficiency comes into play since you have a lot of choice on the frequency/core-count spectrum, versus power, money, space, etc.

[Fnoord]

> Many desktop uses don't care about efficiency, but care about performance.

Why not? I like it when my electricity bill is less severe. For my wallet and the environment alike.