I run a 2K 34" curved NEC or a Dell. Kinda works well for the longer charts context. Plus you can run the laptop, but I do not. I think you can run two at a time, but things can get fussy. A 4K is no problem and it could be one of the huge 50" if you wanted.
HDMI ports are usually the way to go. Your graphics card will determine the monitor resolution you will be able to handle. I have a 27'' connected to the MSI.
Talked myself out of it once more. I started looking at my desktops and the newest is 4 years old, and that is my main trading computer. The backup platform is on my homebuilt which is soon to be 9 years old, and the family computer is 7 years old and is bogging down with all the crap on it. I'll probably keep looking for a laptop deal, but I may build or buy a new desktop first and make it a gaming machine also.
I've had good luck with the ASUS STRIX X99 'Gaming' series, fwiw. Late 2017 model. still going strong, upgraded a few times. 96 GB main ram. I'd recommend linux systems for trading, they dont get bogged down and you can know whats going on under the hood
MSI Apache Pro GE72. Using it since 2016. Very satisfied. Took it for the double cooling,as my previous laptop's cover simply melted because of lack of cooling.
Or DisplayPort. Even integrated graphics can drive multiple displays. I currently run 2 QHD displays off Intel 630 integrated graphics.
display port is my choice or dvi anything else seems lacking. i figured you could either use 1 big monitor or hopefully multiple, does your lappy have 2 ports?
Yes the MSI Raiders, GT, etc. have HDMI and DP, and you can hook both up. A scenario would be a 4K monster on DP and a 2K 34" on HDMI. And the Laptop screen. Total 3. One has to double check the DP and HDMI versions because they support different resolutions at different refresh rates. I think the HDMI does not do 4K well (resolution good, refresh rate bad) until ver. 2.0. DP is usually the preferred way. Even DP 1.2 ver (old) works well at 4K. One other thing, is that one can setup RAID (1) and have a automatic redundant SSD. So now you have backup SSDs, network auto fall over (Wifi->Cell & Ethernet), and screens. Now you can concentrate on trading not IT desk stuff. I pack mine in a Pelican case. Great for moving between places, or even hiding in the basement when I leave for a long time and don't want to leave it out for thieves. The only time I have had problems has been smashing it about in a backpack while moving between places
DP is the preferred one for daisy-chaining 4k monitors out of as single DP port. Check the version though...