XPS 8940, Amazon different from Dell?

@VAer The version you ordered on Amazon does not have a discrete graphics card, only Intel UHD Graphics 750 (integrated graphics). The Dell model you linked to shows a model with a discrete graphics card. 

Thank you. How many monitors can it(this Amazon PC) connect to?

Is discrete graphics card a lot better?

Is it upgradable for more monitors? Is it easy to add graphics card on my own?

Thanks.

How to set up XPS 8940 display resolution as 1920 * 1080? The monitor(Dell E2414H) I am using was connected to Precision T3500 and it can be set as 1920*1080, but I cannot find resolution choice of 1920*1080 in XPS, please see the photo difference.

One photo (1920*1080) is for T3500, the other one is for XPS 8940.

Display resolution is very important for me, so that I can view more content on the screen.

Thanks.

I ordered this PC: https://www.amazon.com/gp/product/B09D7JH9ZC/ 

It is window 11.

Not familiar with hardware, but it seems there is no discrete GPU. Whatever port is, it should support at least 1920*1080

Thanks.

You can easily connect two monitors to your pc via integrated hdmi + DP. Integrated gpu is good for high res monitor but not great for gaming. Discrete gpu varies some very good for gaming and also expensive, other discrete non-gaming gpu give you >2 video port if you need 3+ monitors connected to pc.

you may also connect multiple monitors having DP port if you connect them in daisy chain then connect 1st DP monitor to integrated DP port of 8940. No need for discrete gpu.

How did you connect 8940 to Dell monitor?  Integrated gpu or discrete video card?  Go inside 8940 device manager>display to view your current video adapter. Your 8940 might be using Windows most basic video adapter. It might not have installed the appropriate video adapter for either the integrated UHD 630 graphics of your cpu or discrete gpu.  If this is the case you would need to let Windows 10 update video adapter first.

GPU—Integrated

The specs say this PC model has two DP and one HDMI port for onboard Intel UHD Graphics 630 or UHD 750 Graphics.

IIRC, Intel says UHD 630 and UHD 750 Graphics can support up to three monitors.

You could always use a USB3>video dongle for one monitor, where "video" is a port on the monitor to be connected to the dongle.  Just make sure the dongle support your version of Windows and the "Recommended" (= "Native") resolution on the monitor connected to the dongle.

I wen to Device Manager > Display adapter > Update Driver : it shows "The best drivers for your device are already installed".

At one point, when I restarted PC, it automatically went to 1080p, but only that time. Now I went back to 1024*768, and there is no way to make the change to 1920*1080. It is strange. Window Update is done. Now it stays as 1024*768

@VAer asks, "Is discrete graphics card a lot better?". The answer depends upon what you are trying to do. If you need high resolution and fast refresh rates and have monitors that support that then yes a discrete graphics card in most cases will outperform the integrated graphics. 

"Is it easy to add discrete graphics card on my own?" You may encounter some problems if you try to install a non-Dell graphics card. See this: https://www.dell.com/community/XPS-Desktops/XPS-8940-adding-a-non-Dell-GPU-graphics-card/td-p/7769323

Here are screenshots: Anyone knows how to fix it? Thanks.

Currently I am using Display Port (my VGA  to HDMI adapter will be delivered tomorrow). Thanks.

Try to use hdmi to dvi adapter which are natively similar.

DP and DVI (or hdmi) use quite different voltage on some pin and thus a conversion can be problematic.  DP to VGA conversion would explain why you cannot get optimal resolution.

tip: do not heed Dell prompted bios update even though it claims urgent.  Many users bricked their pc going down that slope.

UHD 750 is supposed to support

• Max Resolution (HDMI)4096x2160@60Hz
• Max Resolution (DP)5120 x 3200 @60hz

If you are using HDMI port it is capable of 4k.  So your current resolution is a far cry from iGPU spec.  
your Dell monitor 

After updating these two, it is making noise. Reboot a few times, still making noise.

This is very unpleasant experience. Something wrong with this PC.