At $279.99 USD, the Elgato 4K Pro is only $30 more than its predecessor, the 4K60 Pro Mk. 2, so if you are getting an internal capture card for the first time, the 4K Pro is a no-brainer.

The Elgato 4K X external capture card is the only device from the Corsair sub-brand that is able to capture 4K 144Hz footage ...

so a separate capture card can really alleviate stress. There's also the option of an internal capture card if you're rocking a two-PC setup.