What matters
The RD280U is the sharper coding fit when vertical pixels and text density lead; the RD320U is the broader mixed-work fit when physical size, image figures, hub speed, and stand movement matter more. Both remain 60Hz programming monitors with 90W USB-C, so neither is a speed upgrade.
Key differences
- Both monitors share the matte programming focus, USB-C power, KVM functions, lighting, and mounting baseline. Because refresh stays at 60Hz, the decision turns on workspace shape and desk hardware rather than motion performance.
- The RD280U uses a 28.2-inch 3:2 panel at 164 ppi in the narrower footprint. The extra vertical workspace and denser text can show more lines of code while taking less desk width.
- The RD320U uses a 31.5-inch widescreen panel at 140 ppi, adds stronger published brightness, contrast, and color figures, supports 10Gbps hub connections, and allows stand pivot. Those gains suit wide multi-window layouts and mixed creative work, but require more desk space.
Who it is for
- Buy the RD280U if long code files, dense text, a 3:2 canvas, and a narrower footprint matter most.
- Buy the RD320U if you need a larger wide canvas, stronger image specifications, faster hub ports, or portrait pivot enough to justify the premium and larger footprint.
Watch-outs
- Buy neither if high refresh is required; both are limited to 60Hz.
- USB-C multi-stream output is not a guarantee of display daisy-chaining from a Mac. Verify the host, cable, and display-output arrangement before buying.
- Measure desk width, depth, and viewing distance for the RD320U, and include any monitor arm, cables, or charging hardware in the total cost.