ROG Swift PG43UQ is the world’s first 43-inch gaming monitor with display screen compression (DSC) technology that delivers native 4K visuals at up to 144Hz via a DisplayPort 1.4 cable.
As for a matching graphics card, most games won't run at 250 fps at 4K, but stand any fighting chance of getting anywhere near that you'll need two GeForce 2080 Tis in SLI - one will only get you just get you half way, and even then, only in a small number of graphically light titles.
Graphics cards don't drive loads through the CPU - it's the other way round. But if you're wanting to play games at 4K at the highest possible frame rates, then you'll need either an AMD Ryzen 9 3950X or an Intel Core i9-9900KS.
Lastly, you'll need to sell one of your kidneys to buy all of this.
Its not only games but also streaming videos from youtube and others should be played at 240 fps or less depending on the content availability.
also, the fps and resolution of the monitor should be backward compatible.