[TIP] Large Amount of Hardware Reserved RAM

[Appletax]

Customer's 2019 Acer laptop has Ryzen 3 3200U and 4GB of RAM with 3.4GB available due to hardware reserved memory.

Installed an 8GB module, and there's just 5.9GB available.

Interestingly, the more RAM installed, the larger the reserved RAM - to a degree.

There's no way to set how much is allocated in BIOS or Windows.


4GB RAM = 3.4GB available, 573MB reserved, 512GB dedicated GPU RAM.

8GB RAM = 5.9GB available, 2.1GB reserved, 2GB dedicated GPU RAM.

12GB RAM = 9.9GB available, 2.1GB reserved, 2GB dedicated GPU RAM.


How do I figure out how much RAM is needed to max out the dedicated GPU RAM?

I am sure the dedicated GPU RAM is nothing like VRAM - perhaps it treats it like VRAM - probably way slower than the real thing.

Why don't I see Intel systems using such a large amount of RAM for the iGPU?

I will stick with the 8GB of RAM given the customer's basic usage (Word, browsing).

 

[Appletax]

My 2021 Lenovo Legion 5 Pro gaming laptop has a Ryzen 7 5800H and RTX 3070 8GB.

It has 148MB of hardware reserved memory. Wonder what it's used for.

 

[Sky-Knight]

Expected behavior to support the integrated GPU. That's independent of the discrete GPU. Not all BIOSs support configuring the memory value, which can be a fixed value or a percentage depending on manufacturer.

 

[Appletax]

Expected behavior to support the integrated GPU. That's independent of the discrete GPU. Not all BIOSs support configuring the memory value, which can be a fixed value or a percentage depending on manufacturer.

Why don't we see Intel doing it?

I guess Intel must be using a max. amount of system RAM for the iGPU as needed - it does not reserve it to make sure it is 100% always available.

How can a person find out what AMD's iGPU's max. dedicated RAM is for their system?

AMD's specs show nothing. Can't find anything.

I know from this person's Acer that 2.0GB is the max. - through testing different RAM capacities.

Would be nice to just look it up and find out what it is and how much RAM is needed to max. out the dedicated GPU RAM.

 

[Sky-Knight]

Why don't we see Intel doing it?

I guess Intel must be using a max. amount of system RAM for the iGPU as needed - it does not reserve it to make sure it is 100% always available.

How can a person find out what AMD's iGPU's max. dedicated RAM is for their system?

AMD's specs show nothing. Can't find anything.

I know from this person's Acer that 2.0GB is the max. - through testing different RAM capacities.

Would be nice to just look it up and find out what it is and how much RAM is needed to max. out the dedicated GPU RAM.

Intel IS doing it, you're just blind for some reason. I've been managing system reserved RAM for integrated GPUs for decades, it's not new and not a new concept.

 

[Appletax]

Intel IS doing it, you're just blind for some reason. I've been managing system reserved RAM for integrated GPUs for decades, it's not new and not a new concept.

Got 2 newer laptops - one with AMD iGPU, one with Intel iGPU.

AMD Radeon 3 Vega has 2.0GB dedicated GPU memory and 3.0GB shared GPU memory for a total of 5.0GB of GPU memory.

Intel UHD Graphics 620 has no mention of dedicated GPU memory - has 3.9GB shared GPU memory.

I don't recall seeing Intel iGPUs with dedicated GPU memory.

Not blind!


Edit: of course, it's not real dedicated memory - real dedicated memory is Video RAM (VRAM) - dedicated just means reserved at all times for the iGPU.

 

[Appletax]

Interesting: my laptop has AMD Radeon integrated iGPU and Nvidia RTX 3070 dGPU. It has a mux switch.

When I have hybrid mode on (iGPU and dGPU both enabled), the system reserves 2.1GB of memory for the AMD iGPU - 13.9GB out of 16GB available.

When I disabled hybrid mode and just use the Nvidia dGPU, the AMD iGPU disappears from Task Manager and Device Manager and the reserve memory goes down to 148MB and there's 15.9GB out of 16GB available.

 

[NviGate Systems]

Intel used to have a section in the BIOS where you could select memory size, in recent years it's become part of the driver, so it can I believe get ram on the fly without any set value defined. So, not really seen anymore in that sense. Also many UEFI interface don't show it.

 

[MudRock]

Yeah check the BIOS. You'll find it to be called "UMA Frame Buffer Size" very commonly (Many times it is named something SANE), and many BIOSes give this big "Warning: Changing this can make the system unstable" -- Yep, you can, IF you dropped it too low. Funny thing is, smallest memory I've seen is 1/2GB, which won't crash anything, just some games won't work.

Don't quote me on this, but if I remember correctly, the 148MB is for boot-time. Ryzen mobile has 0 on-board VRAM, so it has to allocate SOMETHING for boot-time (The text stuff) prior to Windows, UEFI/BIOS and boot managers need to display text, and because dedicated video is 'muxxed' in vs booting to a dedicated video card with the cord plugged into it.

 

[Appletax]

Yeah check the BIOS. You'll find it to be called "UMA Frame Buffer Size" very commonly (Many times it is named something SANE), and many BIOSes give this big "Warning: Changing this can make the system unstable" -- Yep, you can, IF you dropped it too low. Funny thing is, smallest memory I've seen is 1/2GB, which won't crash anything, just some games won't work.

Don't quote me on this, but if I remember correctly, the 148MB is for boot-time. Ryzen mobile has 0 on-board VRAM, so it has to allocate SOMETHING for boot-time (The text stuff) prior to Windows, UEFI/BIOS and boot managers need to display text, and because dedicated video is 'muxxed' in vs booting to a dedicated video card with the cord plugged into it.

My Legion 5 Pro has the UMA Frame Buffer Size in the UEFI. It's set to 2GB. I have a mux switch, which I always have on to disable the AMD iGPU, and that releases the 2GB of hardware reserved RAM.