I've just bought a HP ProDesk 400 G4 Core i5-7500 3.4ghz (2017) and I believe it has Intel HD 630 graphics.
I have a Dell p2415Q display (24" 3840x2160)
1. Will the machine run the display in uhd? and what will be the max res in windows 10?
2. What DP cable should I buy on amazon? (is there a maximum length?)
3. If I add another monitor (same or cheaper 1920x1080) how will I run two monitors? A spliter? or better with a graphics card?
Just getting started with PC stuff, so all help appreciated.
So we can have more information about your system, Download, run, and save the results of this utility as a text file:
Then ATTACH the text file (look at the instructions under the reply window).
According to the pictures on Amazon, you have the SKU of this PC that has both DisplayPort (DP) and VGA connectors.
Your processor supports DP 1.2. This means that you can connect a 4K (3840x2160) monitor at 60Hz. Your monitor has both DP and mini-DP (mDP) inputs, so you can use a DP-to-DP cable or a DP-to-mDP cable.
The VGA port can support a 1920x1080 monitor at 60Hz. Using the VGA connector can sometimes have an impact on the resolution that can be supported by other connectors. I do not know if this will be the case here, but there is an alternative: you can make use of the DP's support for Multi-Stream Transport (MST), which allows multiple monitors to operate independently while sharing the bandwidth of a single DP connection.
MST supports two configurations, daisy-chaining, where the second monitor is connected to a daisy-chain output port on the first monitor (your monitor has such a port, labelled as being the DisplayPort MST Output), or through a MST Hub, which allows one, two or three monitors to be connected in what amounts to a star configuration. Remember, though, that the monitors will share the connection. For example, if two 4K (3840x2160) monitors were connected, they would each only be able to connect at 30Hz. It should be noted, however, that there is enough bandwidth in the DP channel to support one 4K (3840x2160) monitor at 60Hz and one 2K (2048x1080 or 1920x1080) monitor at 60Hz.
Finally, answering in terms of your questions:
Hope this helps,