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Pemalite said:
Bofferbrauer2 said:

Over on the AMD side of things, Rembrandt has shown that AMD can now make really high performing APUs on a tight power budget. A low-power spinoff/successor from there could be used both in an upcoming Switch successor and AMD could use them in their ultra-low-power line (which to this day is still on 14/12nm chips, go figure)

A Rembrandt derivative would probably come with less CU, probably 6 or maybe 8, as 12 would need too much power to feed through. Also possible would be less cores, six cores would be better to keep consumption down without bottlenecking, but I'm not sure if this is an option with AMD and Zen 3. Disabling Hyperthreading is the more likely option in my opinion. Even then, CPU clock speeds would probably go down to somewhere between 2-2.3Ghz and also the GPU clock speeds would need to get cut down somewhat, possibly ~1.6Ghz (No idea what the RDNA2 sweet spot is, so this is just wild guessing).

Since the release is still years away, some Zen4/RDNA3 chip could also be very possible. How that one would stack up in terms of power consumption is still unknown so far however, so we'll have to wait and see what will be possible with those chips in a handheld format.

15-35W mark is where modern processors are at their most efficient (Due to fabrication characteristics dictating some design rules oddly enough).
Rembrandt can suck down about 15w and achieve 1.9Ghz on all 8 Core/16 Threads.
At 20w you start to look at 2.5Ghz... And from there efficiency starts to decline.

That is just all the CPU cores loaded.
At 20w you will start to look at 1.8ghz with all 16 threads loaded and the GPU pegged at the same time.

But you can cut that CPU in half and only have 2/3rds of the CPU functional... And you start to get a very potent and energy efficient chip.

For a handheld, you probably dont need anymore than 4x competent CPU cores... Or maybe even 5 if you wish to dedicate one to the OS/Background so you can have voice/video chat.

I'll have to find the article again, but Zen3+ is remarkably efficient even at locked consumption. While they used a 6800HS (U-series weren't out yet), CPU speeds dropped only marginally between 25W and 15W, 500 Mhz total at worst. Zen 3+ sweet spot seems to be around 2.3Ghz, from there lowering clock speeds only slightly lowers power consumption. At that clock speed, the CPU can consume less than 1.8W per core, so 8c/8t would consume less than 15W at that locked clock speed. Going down to 2 Ghz would lower it to a bit under 1.3W per core without hyperthreading, so roughly 10W for the CPU part on that clock speed. With 6 cores we're at roughly 7.5W.

While this is still too high, going 5nm on that design should be able to drop the power consumption of the CPU part alone to less than 5W on a 6c/6t design. This could make Rembrandt viable for a handheld design with a cut-down GPU with 6-8 CU without needing to become nearly as heavy as the steam deck yet having better battery life.