These cables are directional
The single most important fact: DisplayPort-to-HDMI cables only work in one direction — from a DisplayPort source (your computer or dock) to an HDMI display (monitor, TV, projector). They do not work in reverse. No HDMI-source-to-DisplayPort-display signal will pass through the same cable.
If your computer has HDMI out and your monitor has DisplayPort in, you need an active converter box, not a passive cable. Check the product listing for words like 'unidirectional' or an arrow diagram showing source and display ends.
Match resolution and refresh rate
Cables and adapters are rated for specific combinations such as 4K at 30Hz or 4K at 60Hz. A cable rated for 1080p may still show a picture on a 4K monitor, but the operating system will be limited to what the cable can negotiate — often a blurry or laggy experience.
Decide what you need first: office work is comfortable at 4K 30Hz or 1440p 60Hz, while gaming and smooth scrolling benefit from 60Hz and above. Then confirm both the cable rating and your monitor's capabilities cover it.
Passive cables vs active adapters
Most modern DisplayPort outputs support 'Dual-Mode' (DP++), which lets a cheap passive cable carry an HDMI-compatible signal. This covers the common case of connecting a laptop or desktop to a TV or monitor, and it is what most DisplayPort-to-HDMI cables on the market are.
You need an active adapter instead when the source lacks Dual-Mode support, when converting in the HDMI-to-DisplayPort direction, or when driving unusual resolutions. Active adapters cost more and sometimes need USB power — check before assuming a passive cable will do.
Length, 4K and signal reliability
Higher resolutions are less forgiving of long cable runs. For 4K, keep the cable as short as your setup allows — 1 to 3 metres from a reputable brand is the safe zone. If the picture sparkles, drops out, or the monitor flickers when you move the cable, the run is marginal.
Avoid stacking adapters (for example, DisplayPort-to-HDMI plus an HDMI extension). Every connection is a potential failure point; a single cable of the correct length is almost always more reliable.
Audio and other gotchas
DisplayPort carries audio, and most DP-to-HDMI cables pass it through — but not all. If you rely on monitor or TV speakers, confirm audio support in the listing. Also remember that HDCP copy protection can occasionally cause handshake issues with older displays; unplugging and reconnecting usually resolves it.