Question about Lenovo Legion 5

[magniflcent]

Hello,

I am looking at buying a 2021 Lenovo Legion 5, with 16GB of RAM, a Ryzen 7 5800U, and a RTX 3060 Laptop GPU. Will there be some ram allocated to the iGPU in the Ryzen 7? If so, would turning off hybrid mode or changing something in the BIOS get rid of it?

[SorryBella]

3 minutes ago, magniflcent said:

Will there be some ram allocated to the iGPU in the Ryzen 7?

If the igpu is mainly used with the dedicated graphics turning off. Turning off nvidia optimus or similar hybrid mode would pretty much solves it if available, but the feature availability really depends on laptop to laptop. And of course itll come with more heat and less battery life during medium-low loads.

[jaslion]

30 minutes ago, SorryClaire said:

If the igpu is mainly used with the dedicated graphics turning off. Turning off nvidia optimus or similar hybrid mode would pretty much solves it if available, but the feature availability really depends on laptop to laptop. And of course itll come with more heat and less battery life during medium-low loads.

As far as I know the legion 5 does not allow you to turn off the igpu and always has to have it available.

[porina]

I have a similar model with 5800H and 3070. On that, there is a bios option to either run in dynamic or discrete mode. Dynamic mode is the one where it runs the APU in low power situations and switches to nvidia when a higher power is needed. That mode reserves 2GB of ram for the APU. If you switch it to discrete mode, it only uses the 3070, and you don't lose 2GB of ram to the APU. Check if your model has the same option. If so, run it nvidia only and enjoy. Running the APU has too many quirks and negatives.

 

2 minutes ago, jaslion said:

As far as I know the legion 5 does not allow you to turn off the igpu and always has to have it available.

It might vary with model but mine has discrete mode, which works great and better than having the APU also enabled.

 

 

[jaslion]

1 hour ago, porina said:

I have a similar model with 5800H and 3070. On that, there is a bios option to either run in dynamic or discrete mode. Dynamic mode is the one where it runs the APU in low power situations and switches to nvidia when a higher power is needed. That mode reserves 2GB of ram for the APU. If you switch it to discrete mode, it only uses the 3070, and you don't lose 2GB of ram to the APU. Check if your model has the same option. If so, run it nvidia only and enjoy. Running the APU has too many quirks and negatives.

 

It might vary with model but mine has discrete mode, which works great and better than having the APU also enabled.

 

 

Oh ok then the sites I looked at were wrong makes sense that it can bypass it though since it has the tech for it

 

[magniflcent]

4 hours ago, porina said:

I have a similar model with 5800H and 3070. On that, there is a bios option to either run in dynamic or discrete mode. Dynamic mode is the one where it runs the APU in low power situations and switches to nvidia when a higher power is needed. That mode reserves 2GB of ram for the APU. If you switch it to discrete mode, it only uses the 3070, and you don't lose 2GB of ram to the APU. Check if your model has the same option. If so, run it nvidia only and enjoy. Running the APU has too many quirks and negatives.

 

It might vary with model but mine has discrete mode, which works great and better than having the APU also enabled.

 

 

I would assume it's the same, but I'd  have to check when I get it. Thank you for the help.

[genexis_x]

12 hours ago, porina said:

I have a similar model with 5800H and 3070. On that, there is a bios option to either run in dynamic or discrete mode. Dynamic mode is the one where it runs the APU in low power situations and switches to nvidia when a higher power is needed. That mode reserves 2GB of ram for the APU. If you switch it to discrete mode, it only uses the 3070, and you don't lose 2GB of ram to the APU.

To add on: You can change the APU reserved VRAM in BIOS when Hybrid mode is on, from 2GB to 512MB

[porina]

2 hours ago, genexis_x said:

To add on: You can change the APU reserved VRAM in BIOS when Hybrid mode is on, from 2GB to 512MB

Yes, but the bios explicitly warns you against doing that. IMO the problems introduced by being in dynamic mode just makes discrete mode make much more sense, at least for my use case where the laptop is run off power most of the time and battery life is not a major concern.

[genexis_x]

1 hour ago, porina said:

dynamic mode

Optimus/MSHybrid has been buggy since day 1.