Which is better for gaming?

The Ryzen 7 9800X3D. Its 3D V-Cache gives it a clear lead in most games, often 10–20% higher frame rates than the Core Ultra 9 285K.

Which is better for video editing and rendering?

The Core Ultra 9 285K. Its 24 cores finish renders and exports faster than the 8-core 9800X3D.

Which runs cooler and uses less power?

The 9800X3D. At 120W TDP it is much easier to cool than the 285K, which can draw up to 250W.

Do I need a new motherboard for either?

The 9800X3D uses AM5, so many existing AMD boards support it with a BIOS update. The 285K uses the new LGA1851 socket and requires a new motherboard.

Is the 285K worth stepping up to over the 9800X3D?

Only if your work is heavily multi-threaded. For gaming, the 9800X3D is faster and cheaper to run; for rendering and encoding, the 285K's extra cores pay off.

AMD Ryzen 7 9800X3D vs Intel Core Ultra 9 285K

For pure gaming, the Ryzen 7 9800X3D is the clear pick: its 3D V-Cache and efficient 120W design make it the fastest gaming CPU you can buy, and owners praise its consistent frame rates. The Core Ultra 9 285K is a 24-core workhorse that wins heavily threaded tasks like video rendering and compression, but it runs hot and needs a strong cooler. Choose AMD for a gaming-first build; choose Intel if your work leans on many cores.

Choose the Ryzen 7 9800X3D if you want the highest gaming frame rates and a chip that runs cool and sips power.
Choose the Core Ultra 9 285K if you render video, compile code, or run heavy multitasking and want 24 cores on a new LGA1851 platform.

Prices

AMD Ryzen 7 9800X3D: $399.00 at Jawa.gg (checked today)
Intel Core Ultra 9 285K: $450.00 at eBay (checked today)
Difference: the AMD Ryzen 7 9800X3D is $51.00 cheaper than the Intel Core Ultra 9 285K today