Question Discrete graphics card output through motherboard's output port

[Pimpom]

The other day, I had a reason to want to see the difference between a current AMD IGPU and a decent discrete card. I don't play games but my son does, with an RTX 3060 Ti on a Ryzen 5 5600G system. I asked him to play a fairly demanding game with each GPU in turn.

We were both surprised to see no difference between the two when he switched ports even at ultra settings (we didn't check the fps though). Then, just to make sure, he removed the 3060 Ti card and the frame rate now dropped to unplayable levels.

Then we found that he hadn't installed the AMD driver for the IGPU. Installing it greatly improved the frame rate although it was still quite choppy.

It was evident that the discrete card's output also came out through the motherboard's output port. Is this the way it should be?

 

[TerryLaze]

It was evident that the discrete card's output also came out through the motherboard's output port. Is this the way it should be?

Games will always choose the best GPU available even it's not the one connected to the output, sometimes the games have an option to select which card to use, otherwise you can use windows graphics options to choose for each executable individually.

 

[Pimpom]

Thanks for the reply. What surprised me was that the card's output came out through the motherboard's output port. Now I know.

 

[Richj444]

The other day, I had a reason to want to see the difference between a current AMD IGPU and a decent discrete card. I don't play games but my son does, with an RTX 3060 Ti on a Ryzen 5 5600G system. I asked him to play a fairly demanding game with each GPU in turn.

We were both surprised to see no difference between the two when he switched ports even at ultra settings (we didn't check the fps though). Then, just to make sure, he removed the 3060 Ti card and the frame rate now dropped to unplayable levels.

Then we found that he hadn't installed the AMD driver for the IGPU. Installing it greatly improved the frame rate although it was still quite choppy.

It was evident that the discrete card's output also came out through the motherboard's output port. Is this the way it should be?

No. The discreet GPU does not output via the motherboard ports.

 

[Pimpom]

No. The discreet GPU does not output via the motherboard ports.

Then how does the mere presence of the card make such a HUGE difference when the monitor is connected to the motherboard port?

As I said at the beginning, we didn't check the frame rate but it must have been something like this -

1. At least 50 fps with the 3060 Ti in the slot, whether the monitor is connected to the card's HDMI port or to the motherboard's port. That was without the IGPU driver installed.

2. Maybe 10 fps, maybe less, with the card removed, before installing the IGP driver, i.e., with Windows' generic driver.

3. Maybe 20-25 fps (rough guess) with the IGP driver installed.

 

[ReeDoK]

Then how does the mere presence of the card make such a HUGE difference when the monitor is connected to the motherboard port?

As I said at the beginning, we didn't check the frame rate but it must have been something like this -

1. At least 50 fps with the 3060 Ti in the slot, whether the monitor is connected to the card's HDMI port or to the motherboard's port. That was without the IGPU driver installed.

2. Maybe 10 fps, maybe less, with the card removed, before installing the IGP driver, i.e., with Windows' generic driver.

3. Maybe 20-25 fps (rough guess) with the IGP driver installed.

From my experience, it's possible that the dedicated GPU was sending video signal to the iGPU and then the iGPU sends it to the display. There might be problems, maybe latency and framerate problem, but I think it can work. My motherboard has iGPU multi-monitor support, and if I connect 2 monitors, I can move the game window to monitor that is connected to Intel UHD iGPU, while still running on my AMD card.

 

[Pimpom]

From my experience, it's possible that the dedicated GPU was sending video signal to the iGPU and then the iGPU sends it to the display. There might be problems, maybe latency and framerate problem, but I think it can work. My motherboard has iGPU multi-monitor support, and if I connect 2 monitors, I can move the game window to monitor that is connected to Intel UHD iGPU, while still running on my AMD card.

Thanks for the input. That seems to be the only explanation that makes sense.

 

[geekstrada]

The other day, I had a reason to want to see the difference between a current AMD IGPU and a decent discrete card. I don't play games but my son does, with an RTX 3060 Ti on a Ryzen 5 5600G system. I asked him to play a fairly demanding game with each GPU in turn.

We were both surprised to see no difference between the two when he switched ports even at ultra settings (we didn't check the fps though). Then, just to make sure, he removed the 3060 Ti card and the frame rate now dropped to unplayable levels.

Then we found that he hadn't installed the AMD driver for the IGPU. Installing it greatly improved the frame rate although it was still quite choppy.

It was evident that the discrete card's output also came out through the motherboard's output port. Is this the way it should be?

Hey, necro post, but yes it can use the dedicated GPU through a motherboard port. See this article: https://www.anandtech.com/show/1758...-ryzen-5-7600x-review-retaking-the-high-end/3

Specifically this part:

Anticipating a shift to more USB Type-C displays, AMD is also implementing what they call “hybrid graphics” support on AM5. Unlike previous products where this referred to linking up the integrated graphics with a discrete GPU in CrossFire mode, this time around it refers to being able to being able to use the mobo/iGPU’s display outputs to drive a monitor while using a dGPU to render content. This is largely lifted from AMD’s laptop technologies, where similar techniques are used to allow the dGPU to be powered down when it’s not in use. In the case of desktop processors, this just means every display output will work, regardless of whether it’s plugged into ports coming from the CPU or a discrete video card.

I have an Apple Studio Display connected to my PC with a Thunderbolt 4/USB-C cable via the USB-C (using DP-Alt mode) output of my motherboard using an Intel Arc B580 GPU.