Question Understanding number of integrated motherboard graphics ports VERSUS what is actually supported...

Jul 2, 2022
I'm an EE software engineer but clearly I don't know as much as you smart folks. I am impressed on what I see on this site and it's amazing!

I'd like to buy a PC that will support 3 displays. I've been looking at computers that have motherboards with 3 DP's (or 2 DP's with 1 HDMI, etc.) on the back.
I assumed that an integrated motherboard monitor port would support a monitor, but clearly I am dumb.

Without getting too deep into every different manufacturer, why am I being told that 3 ports does not mean it will run 3 monitors? What is the point of having the 3 holes! ?!? LOL

I will just running a stock trading program (TD Ameritrade ThinkOrSwim to be exact) which does millions of calculations, but only changes a number or two on the screen or maybe moves a chart dot every minute - NOT a lot of FAST display changes.
I've heard about GPU's, etc., and understand how graphics cards have their own processing...

BUT what might I expect if I plugged 3 monitors into a motherboard's 3 DP's?

  1. Will it literally not run 3 monitors and why?
  2. Is the refresh rate of the monitor affected? Will things be blurry?
  3. Will it slow down my i9K PC because it's working so hard to run 3 displays? - I do have a laptop running a USB-HDMI monitor convertor which I'm pretty sure is slowing down my performance, but I really don't know.
  4. I/O bus can't support the traffic?
  5. ???

You can just answer 1 of the options above and provide me some theory or reasons why, or even just say they won't work together because of limited power supply voltage? - then I can move on and make my purchase.

Thank you so much for your expertise and if I can Venmo someone $5 or $10 for solid answer I will. Much appreciated.
Which processor are you looking at? This will tell us how many display outputs it can support.

The only reason why motherboards may have more than what is supported is because the manufacturer doesn't know which CPU you're going to pair it up with. You could get a bottom barrel CPU with the weakest iGPU of that generation and it's not going to support 3 displays, or you can get a higher end CPU with a stronger iGPU and it'll support 3 displays.

As far as your questions go:
  1. It depends on which CPU you get, because which iGPU it's paired up with will tell us how many displays it supports.
  2. No
  3. No. The reason why those USB adapters cause performance hiccups is because the CPU has to do the rendering
  4. There is no I/O bus, it's a direct connection.


1. The cpu of choice will have specific limits as to resolution maximum. It'll also have a certain amount of signal outputs internally. Has nothing to do with the motherboard connections. You can plug in 6 monitors, if the cpu only supports 2 monitors you'll get a signal on 2 and 4 blank screens.

2. Refresh rate is the monitor itself, so no. Fps is different, and depends on what is rendered. 3D like games is massively taxing as there are independent objects with collision etc. 2D like videos is not, it's rolling pictures. Windows is 60fps, video is whatever it was it was taken in, which is commonly 24fps.

3. Answered.

4. Super I/O is capable of far more bandwidth than the igpu can use as it also handles USB traffic etc.

5. ??? Seems like you are trying to find the forest in amongst all the trees. Simple Google would have provided all those answers easily enough, Intel ark would have listed the amount of monitors the cpu in question can support, the maximum resolution supportable as there's a huge difference between 3x 1080p monitors and 3x 4k monitors. A cpu might support 3x 1080p easily enough but be resolution constrained to just 1x 4k monitor, because it's a maximum of, not a guarantee of.


An extra thing to keep in mind. If you have to spend too much to get an iGP that supports the monitor setup you want, you can just buy a cheap GPU. Anything within the last few series of cards from either camp will support 3+ monitors. Even the lowest end ones from 2 gens back. It might be cheaper to buy a card like that and use it than jump up many spaces to get a CPU that does. I haven't worked the math out so I'm not 100% sure.


Whether it ends up cheaper or not is kinda moot when Op is looking at i9 Intels. What matters is it's simply better. Period. The gpu can and will use up resources outside of what a cpu can do, better resolutions, faster rendering of pictures, it's basically having a cpu to do the cpu work and an extra pc to do graphics work.

And that's regardless of the fact that Intel igpu really do kinda suck for anything more than just the basics of sticking windows up on the screen. Add any kind of streaming, 3d, graphical rendering needs and the igpu bogs down like a bandit.

And there's no fix for an igpu. No upgrade, no repair, no change. You get what you get.