Core i5-8400 vs Core i5-9400F

Gaming speed, cores and clocks

The Core i5-8400 and the Core i5-9400F are within a few percent of each other for gaming. In a game, you will not see the difference.

The Core i5-8400 has 6 cores and 6 threads, and the Core i5-9400F has 6 cores and 6 threads. Core counts are the same, so cache size and clock speed decide the difference. Boost clocks are 4 GHz and 4.1 GHz.

Platform, power and price

Both chips use the LGA1151 socket, so they fit the same motherboards. You can swap one for the other without changing the board.

Rated power is 65 W for the first and 65 W for the second. That is close enough that cooling needs will be similar.

At launch the Core i5-8400 cost $182 and the Core i5-9400F $182, which gives 19.8 and 19.8 points of gaming performance per $100. Today's prices will differ.

Which graphics cards each one can feed, and which to buy

At 1080p the Core i5-8400 can feed a card up to the Arc B580 before it holds the card back by more than 10 percent. The Core i5-9400F reaches the Arc B580. Both chips are in the same range for graphics card pairing.

Choose the Core i5-8400 if you want the faster gaming chip and the same or more cores. Choose the Core i5-9400F if you would rather spend the difference on a graphics card, which does more for frame rates in most games.