Essential! To simply display our photos in Photoshop, zoom in, rotate them, even in gigapixels, it is not necessary to have a state-of-the-art and ultra-powerful graphics card. A card with 1 or better 2 GB of RAM is more than enough in 2018. Worse, if we stick to a display function in Photoshop and for everyday use of your computer, a powerful card will do exactly the same job as a first price card and you will not feel the difference in the fluidity of movements or zooms.
The situation is quite different if you play recent video games or if you do video editing, of course. Just to say that it is not automatically necessary to invest large amounts of money in graphics cards to simply do Photoshop editing. With one exception for advanced users, which we will discuss below with the hardware acceleration...
What about 4K screen?
In this case, you will need necessarily recent graphics cards even if you do not buy the most powerful and best RAM-provided cards. Indeed, with 1 GB of RAM you can already manage a 4K screen.
Good news! All recent graphics cards now display the 4K but only on a single screen and "only" in 3840 x 2160 px and not the "real" 4K i. e. 4096 x 2016 px. As most 4K displays are 3840 x 2160 this will not be a problem in practice.
On the other hand, I really draw your attention to their connectivity because to connect your screen - even if it is still a point rarely discussed - they can seriously restrict your display. How? By reducing the refresh rate to 30 Hz. This is the second essential point discussed below when it comes to 4K compatible hardware...
Display refresh rate: 30 or 60 Hz?
In recent years no one paid any attention to it anymore! What should we be aware of? Well, precisely at this rate of image refresh. For a photo, therefore a static image, to be displayed correctly on a screen, it does not need to be refreshed. On the other hand, and we no longer pay any attention to it at all, but in order for our mouse movement, the movement of an enlarged photo in Photoshop and obviously in order for a video not to be jerky, it is then imperative that the image be renewed - or refreshed - at a certain frequency. Well, this comfort is only obtained from 60 Hz:
This rate has become so common that 2018 equipment - AND ONLY with the exception of the 4K - is designed and manufactured to refresh any non-4K computer monitor at this sensitive frequency. Still on my old and "old" 2010 ATI Radeon card, a 5770 with 1GB of RAM, I could connect three Full HD displays while maintaining a refresh rate of 60 Hz.
In fact, the 4K's "greedy bandwidth" makes us return to times that we thought were over (early 2000s) when indeed, only the most recent and powerful maps of the time allowed us to reach this rate on one or more screens... simultaneously!!!!
We are now facing progress - the advent of the 4K and its magnificent display quality - that can take us back to the Stone Age - I exaggerate! - the smooth display of mouse movements, stupidly! You can imagine the surprise if you are not warned...
Be careful about the power of the graphics card! The power alone of a graphics card is therefore not the only important point to display our photos. The refresh rate is just as important if you want to keep a comfortable display with moving images, even if only with our mouse.