Will a 4k monitor work with an old graphics card that does not support 4k?

Question

I'm thinking of getting a new 4k monitor to replace my current 1080p FHD monitor. I usually use my monitor with my personal and work laptops, both of which support 4k. However, I have an old desktop with an old graphics card that only supports 1080p, which I occasionally use.

What will happen if I try to connect a 4k monitor with a HDMI cable to the desktop that doesn't support 4k? Will it work just not in 4k, or will it not display anything at all?

Answer 1

There are 2 possible options.

1. The display will use a lower refresh rate (30Hz vs 60Hz vs 120Hz, probably 30)
2. The display will use a lower resolution

Since both of these options will result in a system usable for web browsing and VoIP (what my old desktop is used for by my sister), you are probably ok

Answer 2

HDMI supports 4K at 60Hz only from version 2.0. Older graphic cards (and even some newer laptops) comes with HDMI 1.4b ports. HDMI 1.4b outputs will work fine on 4K, but only at 30Hz (and 30Hz is not nice).

BUT, if your graphics card has a DisplayPort output, it would probably work just fine. I have here an AMD R9 280X GPU and it works fine at 4K 60Hz, but I had to buy a DisplayPort cable, because HDMI outputs didn't work at 60Hz on 4K.

If you don't have DisplayPort outputs on your Graphics card/laptop, you might consider using a 2560x1440 monitor instead of a 4K one. It gives the biggest resolution possible on a HDMI 1.4b output at 60Hz.