Running NVidia and Intel GPUs at the same time (to different outputs)

[AtoningUnifex]

I am looking for a clevo notebook that supports running discrete (NVidia) GPU and the integrated Intel GPU at the same time, with each connected different displays (most likely dGPU connected to external monitors and iGPU connected to the internal display panel).

 

In a post from late last year, a reliable poster (Prema) said:

Quote

The Skylake P6xxRx models will have a MUX (no Optimus) between iGPU, dGPU and internal screen. ALL external ports are directly connected to the dGPU only.

So while using the internal screen, which are now all eDP (mainly THX to g-sync compatibility) the system can also run on iGPU only (of course no g-sync on iGPU).

 

Can anyone confirm this statement (which based on the wording was made before the release of the models in question)?

 

I think this implies a BIOS setting (or some other way) for choosing whether the internal panel is connected to the dGPU or the iGPU.

 

If the internal panel is connected to the iGPU, can the dGPU still be running with external panels connected to it? In other words, both GPUs visible to the OS at the same time with different monitors/panels connected to each?

[Khenglish]

You can't use both the iGPU and dGPU simultaneously on laptops to drive displays. You are either stuck with iGPU, stuck with dGPU, or can choose between 100% iGPU or 100% dGPU. You can't use both to drive all display outputs at once.

[AtoningUnifex]

@Khenglish: are you saying this about all laptops? Or just the Clevo range I was asking about?

 

It is true that most laptops these days only allow a single GPU to be connected to the outputs at a time, but this isn't necessarily true of all laptops, particularly those with mux chips. Before Optimus became common, some laptop models used mux chips to allow both GPUs to be running at the same time with different outputs (although which outputs could be used with which GPUs varied from model to model). This appears to be rare these days, but that doesn't mean NO laptops do this anymore.

 

According to a post by @Prema (apparently before release):

Quote

The Skylake P6xxRx models will have a MUX (no Optimus) between iGPU, dGPU and internal screen. ALL external ports are directly connected to the dGPU only.

 

Can someone confirm this is the case?

 

And if so, when the internal display panel is connected to the iGPU, is the dGPU turned off and the external ports non-functional? Or can the dGPU be enabled given the external ports are connected to it?

[Khenglish]

7 hours ago, AtoningUnifex said:

@Khenglish: are you saying this about all laptops? Or just the Clevo range I was asking about?

 

It is true that most laptops these days only allow a single GPU to be connected to the outputs at a time, but this isn't necessarily true of all laptops, particularly those with mux chips. Before Optimus became common, some laptop models used mux chips to allow both GPUs to be running at the same time with different outputs (although which outputs could be used with which GPUs varied from model to model). This appears to be rare these days, but that doesn't mean NO laptops do this anymore.

 

According to a post by @Prema (apparently before release):

 

Can someone confirm this is the case?

 

And if so, when the internal display panel is connected to the iGPU, is the dGPU turned off and the external ports non-functional? Or can the dGPU be enabled given the external ports are connected to it?

 

All laptops with a mux select either all outputs as dGPU, or all outputs as iGPU. While it is possible for the manufacturer to easily expand this to pick and choose which GPU does which, no one ever implemented doing so. This is true for all Clevo, MSI, and Alienware systems. Thinking back, during the Sandy Bridge era there may have been a system or two that had the dGPU only wired to the displayport, but that was the only exception (M18x R1 and M17x R3). I might not even be right about that, but I vaguely remember people saying their DP port only worked in PEG mode.

[AtoningUnifex]

@Khenglish so is the post by @Prema wrong?

 

He said that the external ports would be connected directly to the dGPU, you're suggesting they aren't (the mux chip switches all outputs between IGPU and dGPU).

 

I understand that the norm for clevo models is as you have stated, but the post by @Prema suggests the P6xxRx range could be a (welcome) exception.

 

Can anyone confirm which way this is for a clevo P6xxRx model (e.g. P650RP6-G)?

 

Is there an email/contact at clevo that could answer the question?

[Khenglish]

What the P6xxRx systems likely do is power off the dgpu when the igpu is driving the internal lcd. Notice that Prema also said "no optimus". It sounds like the igpu mode is intended only for battery life extension purposes, and the external display ports will simply not work at all in this mode.

[AtoningUnifex]

@Khenglish - thank you for your response. Your educated guess about the likely setup is probably right. Certainly if there is no optimus, then it would be important to have an iGPU only mode to support a low power / longer battery life use case.

 

I would like to find a way of getting actual confirmation, not educated guesses (as much as I appreciate the educated guesses).

 

I have found it difficult getting reliable answers for things like this from the clevo vendors (such as Sager in the US and Metabox in Australia). Sometimes I have been given contradictory answers from different vendors and been left stuck not knowing which is correct. Official manuals (when available) do not provide information of this sort.

 

Does anyone know if there is a suitable technical contact at clevo, or is the only option to go through a clevo vendor? Are one of the other clevo vendors (such as one in Europe) better at answering this sort of thing?