The iGP can access shared memory the same as with any modern system. I'm confused where you got this idea from.

There is a huge difference between on-die and off-die memory. Where that shared memory is located matters immensely.

Assuming you're referring to Apple Silicon's memory bandwidth, that is not necessarily because the memory is on-die. The bandwidth comes from having more channels to access memory. This gives the SoC a wider bus to increase throughput vs. your typical x86 system with two channels. For whatever reasons Intel/AMD decided that two channels is all the typical consumer chips can support now so it's on them.

Ah I see, thanks for breaking it down.

On laptops right? Weve seen more channels for years elsewhere

Yes, on laptops, but even on most desktops now too. Higher number of channels is getting more limited to server systems.

You mentioned Strix Halo, which also has off-die memory. Strix Halo does have a real advantage from its wider memory bus (four channels for 256 bit instead of 128 bit), but Strix Point is equivalent-ish to Intel's platforms like Panther Lake or Arrow Lake in terms of memory setup.

In fact, Intel also had Lunar Lake, which had on-package memory. However, it was still limited to 128-bit dual-channel, so there weren't really many performance benefits; it did however help with power efficiency.

I appreciate everyone's corrections here, my apologies. I clearly misunderstood the situation.

Macs or other competing systems don't have on-die memory.

(Except for the caches, which everybody has)

Nonsense, Apple has on package memory and the primary reason for that is overall packaging and layout not performance

It is much slower, but still possible to run on ram

There is no VRAM in this laptop so how is it not unified? The CPU and GPU both share the same memory.