Quote from: jrharbort on August 13, 2022, 03:03:14Quote from: wolfwood on August 12, 2022, 16:23:01I'm a little confused, because Lenovo lists all the new AMD 6x50U laptops as using dual channel memory, but you report that the Z13 is quad channel. where did you find this information? and do you think it's true of the T14s/X13 gen 3 etc. as well?
Each DDR5 module is considered to be running in dual channel mode (for some reason), so two modules results in "Quad Channel" mode.
But the width of one channel LPDDR5 (as and LPDDR4) - only 32 bits. And the amount for the "Quad" mode is all the same old 128 bits as typical for a conventional (not soldered, in slots) two-channel mode with 64 bits per channel. 32 x 4 = 64 x 2 for a conventional DDR5. You do not get large throughput with LPDDRX. But "6400" is 6400 x 128 (full bus width) / 8 (divide by the byte width) = 104.2 Gb/s.
In practice, we have only 48-49% of the full bandwidth for LPDDR5 6400. This is a shame for Lenovo, and in general for LPDDR5 6400 in any laptop, because even in the best solutions, it gives a maximum of 67-70GB/s (65-67% from full throughput, in theory) in practice.
Why is it so important? This is extremely important for the future support of 8K monitors connected by Display Port 2.0 (HDMI 2.1 is not capable of transmitting lossless 8K signal even for 24 bit mode, too narrow maximum bitrate). This is especially critical for the video chips built into the processors, which use shared memory of the system memory and dividing its throughput with OS and software and other devices on the system bus. As the practice of using 4K monitors with igpu, so that there are no lags and frizes on the external monitor, if it is not directly connected to a discrete video chip, the throughput diverted to it from system memory bus should not exceed 8-12% of the total throughput system memory bus. Otherwise, problems begin. Purely empirically.
Those. 8K Signal requires a 4 times larger throughput, obviously, neither DDR4 3200 nor even DDR5 6400 are capable of serving 8k monitor, more precisely, DDR5 4800+ is theoretically capable of, but the real performance is completely disgusting (and even such shameful subsidence as in Z13 is completed by the picture) today from the point of view of the memory bus efficiency.
In general, so far if _any_ laptop, even with i3 (and even with celeron) will not be able to operate in memory at a speed of at least 85-90GB/s for serve 8k panels, as a mass phenomenon (8k screens) on the market can be forgotten.
The funny thing is that the 8K panels were ready in 2014, but there was no interface for it by one сable. For 3 years, as there is Display Port (on paper) and only in 2022 finally AMD promises official support for DP2.0 in Ryzen 7xxx. But again, there is no sense in it, because a standard computer on 7xxx is unlikely to reach the indicated minimum for memory throughput (probably). Therefore, apparently it will be required for another 3-4 years, until everyone gets dram throughput for minimal 85-90Gb/s, and most of the computer and laptops will not have a memory subsystem with a this memory speed of at least 100GB/s+. And then we will go to the world 8k panels (in 2D and in light 3D of course).
Well, if nothing terrible will happen to the world and the world division of labor and the civilization will be alive and will develop further, then in 15 years we will receive 8k games with acceptable FPS (60+ in the ultra quality).
And 8k picture on the screen around 32" is practically not distinguishable from the reality in detail for eyes, i.e., almost analog by visually (as has already become the norm on smartphones with ppi above 400).
It remains only to get 3d chips capable of rendering the picture as close to the real world and virtual reality will become a reality (sorry for the pun)...
But what amazing - discrete video chips for many years (10 minimum) were able to serve 8K monitors (in 2D of course, about 3D and now there is no talk, they can't cope with 4K), because Their GDDRX memory has long exceeded the speed of 100GB/s. But there was no DP2.0 interface. And when he appeared in 2019, Covid came and everything apparently scored on a new standard. So, for the first time in the history of the IT industry, the implementation of the standard was delayed for 3 extra years ...
Deutsch
English
Español
Français
Italiano
Nederlands
Polski
Português
Русский
Türkçe
Svenska
Chinese
Magyar