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People say this, but it’s a trite trivialization of the architectural choices made beyond just the ISA. When AMD/intel have moved to the same or comparable no

by dagmx 2y ago

People say this, but it’s a trite trivialization of the architectural choices made beyond just the ISA. When AMD/intel have moved to the same or comparable nodes, they’re not catching up for perf/watt. Lunar Lake will be on the same N3E as M4, so we’ll have to see how it compares.

AnthonyMouse 2y ago
> When AMD/intel have moved to the same or comparable nodes, they’re not catching up for perf/watt. They are though? If you compare the Apple and AMD processors that are both on e.g. TSMC 5nm, the AMD ones have if anything better performance per watt. Compare the 7945HX3D to any Apple CPU on the same 5nm process with a similar TDP and the 7945HX3D will generally have similar if not better performance. But people keep doing comparisons right after Apple is the first to release a CPU on a new TSMC process, and naturally if you don't compare like with like, the newer process is more efficient. Another reason people keep getting confused is that AMD isn't afraid to go back and release updated models of older cores on their original process nodes. So for example the 7730U is from 2023, it's just a year old, but it's Zen 3 on the 7nm process they've been using since 2019. Meanwhile the "real" 2023 release was Zen 4 on 4nm (e.g. 7840U), but don't pick the wrong one to do your comparison.
- KingOfCoders 2y ago
  "Compare the 7945HX3D to any Apple CPU on the same 5nm process with a similar TDP and the 7945HX3D will generally have similar if not better performance." Sounds interesting, do you have numbers - s I get this argument often, that on the same node, Apple is so much better.
  - AnthonyMouse 2y ago
    So here's each vendor's first CPU on TSMC 5nm. This is actually the only process they've both used, and AMD only used it for a couple of models -- they tend to use all the ones Apple doesn't (7nm, 6nm, 4nm vs. 5nm and 3nm), which makes direct comparisons rare. But this is one: https://nanoreview.net/en/cpu-compare/apple-m1-ultra-vs-amd-ryzen-9-7945hx3d https://nanoreview.net/en/cpu-compare/apple-m1-ultra-vs-amd-... They both have a similar TDP, a similar number of cores and the performance on most tests is similar or better for the 7945HX3D.
    - KingOfCoders 2y ago
      <3 OT: I think it also shows the bad iGPU compared to Apples offerings, so too many x86 laptops have additional GPUs, which reduces battery life (we'll see what Strix brings) Also both have 16 performance cores, but the Ryzen is faster in multicore. The Ryzen is one year later b/c due to node access/ costs. Doesn't look like "far behind".
      - AnthonyMouse 2y ago
        There is nothing inherently inefficient about a discrete GPU. Discrete GPUs often have extremely good performance per watt. That's just not the same thing as having a low TDP. Performance per watt is higher when something is twice as power hungry but three times faster.
        KingOfCoders 2y ago
        Not an electrical engineer, my GPU board has lots of additional chips and VRMs, and I do think those should take additional power. All of these are cooled which means they convert power into heat, so I would assume a discrete board draws more power than a SoC. But as I've said, not an electrical engineer (Just some electrical engineering exams at university).
        AnthonyMouse 2y ago
        In principle you can shut off anything when it's idle and get its power consumption arbitrarily close to zero. Discrete GPUs obviously use more power because their use case is when the iGPU isn't fast enough. Hypothetically you can make a discrete GPU with the same performance as an iGPU and it would be no more power hungry. These have occasionally been available, basically monitor cards for CPUs without an iGPU etc. But the ones with a lot of fans and VRMs have them because they do indeed use a lot of power -- which isn't the same as having poor performance per watt, because they're also really fast.
    - paulmd 2y ago
      You have to be careful of citing spec-sheet TDPs because AMD allows their CPUs to boost way above the configured TDP where for apple it’s normally obeyed, and usually not reached unless it’s a mixed cpu-gpu load like gaming. Pointing to TDP as if it meant anything compared to actual power measurements is usually a mistake. It doesn’t mean anything anymore. I really hate it as much as anyone else, I love architectural comparisons/etc... but you have to look at actual measurements from actual devices in a particular workload. Which, again, is very unfortunate since most reviewers don't do that, certainly not for more than one or two workloads. Cinebench R23 is also not a particularly great test compared to SPEC2017, Geekbench 6, or Cinebench 2024, and most vendors still haven’t switched over even to the newer CB2024. Generally the older tests tend to give x86 a bit of a boost because of the very simple test scenes/lack of workload diversity. (I was looking at this when M3 Max MBPs came out and 7840HS was the current x86 hotness etc... just very few reviewers with direct CB2024 numbers yet and fewer with actual power measurements, let alone anyone having any other workload benched... geekerwan and notebookcheck seem to be the leaders in doing the actual science these days... save us, Chips And Cheese...)
KingOfCoders 2y ago
As others have been pointing out, Lunar Lake is on N3B and N3E (M4) is booked up by Apple.

by dagmx 2y ago

AnthonyMouse 2y ago

> When AMD/intel have moved to the same or comparable nodes, they’re not catching up for perf/watt. They are though? If you compare the Apple and AMD processors that are both on e.g. TSMC 5nm, the AMD ones have if anything better performance per watt. Compare the 7945HX3D to any Apple CPU on the same 5nm process with a similar TDP and the 7945HX3D will generally have similar if not better performance. But people keep doing comparisons right after Apple is the first to release a CPU on a new TSMC process, and naturally if you don't compare like with like, the newer process is more efficient. Another reason people keep getting confused is that AMD isn't afraid to go back and release updated models of older cores on their original process nodes. So for example the 7730U is from 2023, it's just a year old, but it's Zen 3 on the 7nm process they've been using since 2019. Meanwhile the "real" 2023 release was Zen 4 on 4nm (e.g. 7840U), but don't pick the wrong one to do your comparison.

KingOfCoders 2y ago
"Compare the 7945HX3D to any Apple CPU on the same 5nm process with a similar TDP and the 7945HX3D will generally have similar if not better performance." Sounds interesting, do you have numbers - s I get this argument often, that on the same node, Apple is so much better.
- AnthonyMouse 2y ago
  So here's each vendor's first CPU on TSMC 5nm. This is actually the only process they've both used, and AMD only used it for a couple of models -- they tend to use all the ones Apple doesn't (7nm, 6nm, 4nm vs. 5nm and 3nm), which makes direct comparisons rare. But this is one: https://nanoreview.net/en/cpu-compare/apple-m1-ultra-vs-amd-ryzen-9-7945hx3d https://nanoreview.net/en/cpu-compare/apple-m1-ultra-vs-amd-... They both have a similar TDP, a similar number of cores and the performance on most tests is similar or better for the 7945HX3D.
  - KingOfCoders 2y ago
    <3 OT: I think it also shows the bad iGPU compared to Apples offerings, so too many x86 laptops have additional GPUs, which reduces battery life (we'll see what Strix brings) Also both have 16 performance cores, but the Ryzen is faster in multicore. The Ryzen is one year later b/c due to node access/ costs. Doesn't look like "far behind".
    - AnthonyMouse 2y ago
      There is nothing inherently inefficient about a discrete GPU. Discrete GPUs often have extremely good performance per watt. That's just not the same thing as having a low TDP. Performance per watt is higher when something is twice as power hungry but three times faster.
      - KingOfCoders 2y ago
        Not an electrical engineer, my GPU board has lots of additional chips and VRMs, and I do think those should take additional power. All of these are cooled which means they convert power into heat, so I would assume a discrete board draws more power than a SoC. But as I've said, not an electrical engineer (Just some electrical engineering exams at university).
        AnthonyMouse 2y ago
        In principle you can shut off anything when it's idle and get its power consumption arbitrarily close to zero. Discrete GPUs obviously use more power because their use case is when the iGPU isn't fast enough. Hypothetically you can make a discrete GPU with the same performance as an iGPU and it would be no more power hungry. These have occasionally been available, basically monitor cards for CPUs without an iGPU etc. But the ones with a lot of fans and VRMs have them because they do indeed use a lot of power -- which isn't the same as having poor performance per watt, because they're also really fast.
  - paulmd 2y ago
    You have to be careful of citing spec-sheet TDPs because AMD allows their CPUs to boost way above the configured TDP where for apple it’s normally obeyed, and usually not reached unless it’s a mixed cpu-gpu load like gaming. Pointing to TDP as if it meant anything compared to actual power measurements is usually a mistake. It doesn’t mean anything anymore. I really hate it as much as anyone else, I love architectural comparisons/etc... but you have to look at actual measurements from actual devices in a particular workload. Which, again, is very unfortunate since most reviewers don't do that, certainly not for more than one or two workloads. Cinebench R23 is also not a particularly great test compared to SPEC2017, Geekbench 6, or Cinebench 2024, and most vendors still haven’t switched over even to the newer CB2024. Generally the older tests tend to give x86 a bit of a boost because of the very simple test scenes/lack of workload diversity. (I was looking at this when M3 Max MBPs came out and 7840HS was the current x86 hotness etc... just very few reviewers with direct CB2024 numbers yet and fewer with actual power measurements, let alone anyone having any other workload benched... geekerwan and notebookcheck seem to be the leaders in doing the actual science these days... save us, Chips And Cheese...)

KingOfCoders 2y ago

As others have been pointing out, Lunar Lake is on N3B and N3E (M4) is booked up by Apple.