Intel released the Core i5-9400F processor in early 2019 as a budget gaming U. The low price was thanks to the removal of all integrated graphics, which is a fine trade-off if you're going to be installing a dedicated graphics card anyway (and if you're serious about gaming, you should be). The U has already dropped in price a few times since its release, but now it has fallen to an all-time low of $119.99. That's $30 below the usual price, and $80 below the original MSRP.
The 9400F has six cores (no Hyper-Threading), a boost clockspeed of up to 4.10GHz and base clock of 2.9GHz, a TDP of 65W, and for up to 128GB of memory. The 'F' means there's no integrated graphics , so you absolutely need a dedicated GPU to get any kind of video output—just like with most of AMD's Ryzen processors.
It's worth noting that you can currently get a Ryzen 5 2600 processor for just a few bucks more. That U has twice as many threads as the 9400F, but the Intel chip comes out slightly ahead in gaming and other tasks that depend on strong single-threaded performance.
Just make sure to you have a compatible motherboard before buying. Any B360, H310, H370, Q370, Z370, or Z390 model should work.
