Genuine question, from someone that won’t upgrade from their M1 Air: what difference does it make for most users? Where would that extra 50GB/s be felt?
Instead, most of the felt responsiveness on the M1 comes from the insane memory bandwidth. Everything from launching apps to task swapping to garbage collection events in various languages gets a boost from the lower latency and higher bandwidth.
> The M1 doesn't really benchmark in pure CPUs tests much higher that the Intel chips it replaced
It does. See Cinebench 2024 ST at https://www.cpu-monkey.com/en/compare_cpu-apple_m1_pro_10_cp... : M1 Pro is 1.6x faster than Intel Core i9-9880H installed in the latest (2019) 16" Intel MBP (see the table at https://en.wikipedia.org/wiki/MacBook_Pro_(Intel-based)#Tech...).
> Instead, most of the felt responsiveness on the M1 comes from the insane memory bandwidth.
False. Extra bandwidth is there for and meaningfully improves the performance of the GPU, not the CPU. CPU can not even access all of that bandwidth in Apple M-series designs in the first place:
"While 243GB/s is massive, and overshadows any other design in the industry, it’s still quite far from the 409GB/s the chip is capable of. More importantly for the M1 Max, it’s only slightly higher than the 204GB/s limit of the M1 Pro, so from a CPU-only workload perspective, it doesn’t appear to make sense to get the Max if one is focused just on CPU bandwidth."
(source: https://www.anandtech.com/show/17024/apple-m1-max-performanc...)
Furthermore, even within the bandwidth actually available, it's just a matter of fact that extra bandwidth barely if ever really makes a dent in CPU limited (as opposed to GPU limited) applications. See https://youtu.be/omumzW1AtGE?t=500 as an example of one of the studies on the overall subject.
> a boost from the lower latency
False. M-series systems have slightly _higher_ system memory to/from CPU latency, and drastically higher system memory to/from GPU latency (especially compared to other iGPU solutions).
See https://www.anandtech.com/show/17024/apple-m1-max-performanc... for the CPU side: 111 ns for M1 Max CPU to DRAM.
See https://www.anandtech.com/show/16680/tiger-lake-h-performanc... for the same data for Intel i9-11980HK as a ballpark comparison point: 101 ns. Apple's results are basically inline with everything else in the industry, and are in fact slightly worse on latency.
For GPU side, see https://chipsandcheese.com/2023/10/31/a-brief-look-at-apples... :
"DRAM access takes more than 342 ns at the 128 MB test size. Going further sends latency beyond 400 ns, perhaps due to TLB misses. M2 Pro thus has higher DRAM access latency than AMD’s Phoenix, which has similar memory access latency to recent discrete GPUs."
You will see: DRAM latency from M2 Pro's iGPU is up to 475ns, while iGPU on AMD 7840HS peaks (on the bad side) at 270ns. M2 (non-Pro) does better than M2 Pro peaking at 330ns or so, still roughly 20% worse than AMD.
I'm sorry, but the exact negation of everything you said is in fact true.