[NAME] Ong  - Always include exact PC model and version of Windows in your posts. Do you only have onboard Intel Graphics without an add-in video card? Make sure the cable you buy works DP(PC)>HDMI(monitor). They're typically not "reversible" so you just can't turn a HDMI(PC)>DP(monitor) cable around...
I am intend to buy A monitor (LG32SQ730S-W), which have only HDMI nut not DP input, can I use a "DP to HDMI cable" to get the UHD display?  (as this DEll PC must use DP port to get UHD and HDMI port only support FHD.)
DP to HDMI cable