If you’re looking at how the two chips feel when you’re actually using the computer, the newer Intel Core i5‑10400F is the clear winner for most people.
Office and everyday work
When you open a word processor, a spreadsheet, a few email tabs and maybe a browser with a handful of tabs, the 10400F runs everything a little faster. It can keep all those background tasks running smoothly because it has twice as many “threads” (think of them as little helpers) as the older 9350K. With the 9350K you might notice a little lag if you have many applications open at once.
Gaming
For games you’ll also find the 10400F a bit snappier. It can feed the graphics card more quickly thanks to slightly faster memory and because it can juggle more background work while the game is running. The 9350K is still capable, but the 10400F usually gives you a smoother experience.
Video editing and heavy multitasking
If you edit videos, render photos, or run several programs at the same time, the 10400F’s extra helpers (8 threads versus 4) make a noticeable difference. The newer chip also uses faster RAM, so the data your programs need is delivered a little quicker.
Power and heat
The 10400F uses only about 65 W of power, while the 9350K needs 91 W. That means the 10400F runs cooler and is easier on the electricity bill. You won’t need a huge cooling system to keep it comfortable.
Other points to keep in mind
So, for office work, gaming, video editing, or just having many programs open at once, the Intel Core i5‑10400F is the better choice. The 9350K might still appeal if you want to squeeze out extra speed through tweaking or need that special memory support, but for most people the newer, more efficient 10400F is the way to go.
