2 Graphic cards for multiple montor setup (Gaming and working)

[Kainite311]

I tried to wade thru some previous forum posts and google what I could but none seem to answer a basic question about using 2 graphic cards in 2 PCE slots. So for reference I am trying to build my computer to support 6-9 montiors. Only one monitor will be a gaming monitor, the rest are work and don't require any graphic power other then to hit 1k resolution. So I am looking at getting a decent gaming card to run 1-4 monitors (as needed, depending on what other card is and final monitor count), and a second low end multi monitor output card (running 3-6 outputs, depending on card). Far as I have learned, not a problem yet. Basically run a gaming card in top slot, and whatever I decide in second slot (just to avoid complication they will both be same manufacter either both AMD or Nvidia)

 

The question I have then is what happens to the performance of the gaming card? I am looknig at AM5 670 boards that have 2 PCIx16 slots. The issue I am seeing is that buried in the technobabble is that when you use both PCI x16 slots at the same time they become x8/x8 speed instead. How much does this affect performance of the gaming card in real world FPS terms (please don't just say half, because thats not what actually happens realworld wise...).

 

Or if you have a better solution to run at least 6 montiors and still have good performance on one monitor running games I am open to better options that I am not aware of.... (running 6 montiors with display port in/outs to daisy chain is not an option as the cost of 6 new montors is beyond my budget) and far as I know nvidia 3000/4000 series and amd 6000/7000 series both list they can only support up to 4 monitors in their tech sheets regardless of number of outputs.

[Eigenvektor]

1 hour ago, Kainite311 said:

The question I have then is what happens to the performance of the gaming card? I am looknig at AM5 670 boards that have 2 PCIx16 slots. The issue I am seeing is that buried in the technobabble is that when you use both PCI x16 slots at the same time they become x8/x8 speed instead. How much does this affect performance of the gaming card in real world FPS terms (please don't just say half, because thats not what actually happens realworld wise...).

Depends on the card. For most, PCIe bandwidth is not a limiting factor and there's minimal impact.

 

Some lower end cards like the RX 6500 XT only have PCIe x4. They suffer roughly 20% lower performance if you go from PCIe 4.0 to PCIe 3.0, because of this. Then you have cards like the RX 6600 (XT) that only have PCIe x8, and there's very little difference between PCIe 4.0 and 3.0. Most higher end cards have PCIe x16, but the performance impact of either limiting them to x8 or going to PCIe 3.0 is minimal.

 

There are some benchmarks here:

https://www.techpowerup.com/review/amd-radeon-rx-6600-xt-pci-express-scaling/

https://www.techpowerup.com/review/nvidia-geforce-rtx-3080-pci-express-scaling/

https://www.techpowerup.com/review/nvidia-geforce-rtx-4090-pci-express-scaling/

[Kainite311]

Thank you for the info. Was looking at maybe AMD 7900 or Nvidia 4070 for gaming. Still overkill for me as I am only running 2k for gaming, but was trying to future proof myself incase I decided to change setup (such as replacing 4 21" monitors with a 48" and then using it to display 4 windows the same size - so far I have decided against this as pixels and text in particular look blurry when your sitting desk length away to such a large screen...)

 

So it looks like a loss of 1-2% across most games. Good enough for me. I was concerned it might be like 30+% FPS loss...