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> So let's see what happens when Intel and AMD step to smaller processes and switch to much faster memory (ddr5 as apple has done). Maybe the gap is large in en
by daneel_w 4y ago
> So let's see what happens when Intel and AMD step to smaller processes and switch to much faster memory (ddr5 as apple has done). Maybe the gap is large in energy consumption, but not in total performance.
There are 18 months worth of benchmarks from the Apple M1 that show that the gap really is large in total performance, and the "standard" M1 doesn't use DDR5, it uses the same DDR4 memory everything else uses. The observed performance gap is larger than what we can see happen between DDR4 and DDR5, and larger than what is expected to happen for AMD's and Intel's x86 between 7 and 5 nm.
- pclmulqdq 4y agoApple uses LPDDR RAM which is a very different protocol. It is actually faster than DDR, and this may be a big part of the performance difference. For obvious reasons, desktop CPUs cannot use LPDDR RAM, because you can't put it in DIMM form.
- daneel_w 4y agoAre you really sure about that? I thought LPDDR is all about low power consumption - running at half the frequency but making up for it by twice the bus width, ending up at same performance but with an emphasis on the LOW POWER part of its name. Add.: or maybe I got it the wrong way around; smaller bus width but same performance due often being clocked faster. Either way I cannot find anything suggesting LPDDR offers practically faster performance on memory-bound operations than the DDR equivalent, but I'd love to see some tech details and numbers explaining how it works.
- wmf 4y agoIn Apple's case, it's the same width (M1/2) or much wider (Pro/Max/Ultra) and also clocked faster (6400 vs. 4800).
- pclmulqdq 4y agoLPDDR used to be about power consumption. It is not any more. DDR uses a lot of power for I/O and SERDES links to maintain a modular form factor, and LPDDR uses a lot less power by having worse signal integrity and lower swings. They run the memory cells and the I/O faster, and as of LPDDR4 it is now significantly faster than the DDR memory products available.
- uniqueuid 4y agoYeah I was imprecise there, the M2 is using LPDDR5. So I'm expecting Apple to stick with that for future macs of this generation. The gap between M1/M2 is pronounced in laptops but you can get faster (and hotter) multicore CPUs. Single-core is also not the same gap that it was because Rocket Lake has caught up and Zen3 had less of a gap to begin with.
- daneel_w 4y agoAnd M2 benchmarks aren't even out yet. The topic will be yet more interesting in the coming months.
- uniqueuid 4y agoThey are absolutely out, because the M2 MBP is publicly available. https://browser.geekbench.com/v5/cpu/15482594 https://browser.geekbench.com/v5/cpu/15482594
- fxtentacle 4y agoOh so the M2 is a lot slower than Samsung phones? Samsung Galaxy S20 FE 5G = 2147483647 multi-core score https://browser.geekbench.com/v5/cpu/15129294 https://browser.geekbench.com/v5/cpu/15129294 But only 8928 multi-core for the new M2. Or maybe that page is kinda unreliable?
- sph 4y agoThat number is 2^31-1, the maximum number representable as a signed 32bit integer. Sounds like someone managed to push their fake Geekbench score. "Text compression: 22.8 TB/s". How long does the battery last though?
- fxtentacle 4y agoYes, that's what I wanted to say. Geekbench scores aren't that trustworthy.