HP USB-C Dock G5 vs Thunderbolt Dock G4: keep or replace?

Compare the requirement, not the generation number

HP: USB-C Dock G5 datasheet, July 2020, compatibility on page 2 · HP Thunderbolt G4 Dock data sheet and variant notes

A useful example: EliteBook 840 G8

HP’s reviewed G8 SKU sheet lists both products. That gives you a supported-model starting point, but the actual screens still decide whether a change is useful. If both screens already extend at the required modes and charging is adequate, a replacement has no established benefit for that requirement. HP: EliteBook 840 G8 5Z5B5EA specifications and listed docking accessories

Before buying a used G4

1. Identify the 120 W supply and intended host cable; do not confuse it with the workstation combo version.
2. Write down each monitor’s mode and planned output socket.
3. Check any required HP wake, network or management functions for the exact laptop.
4. Include missing power supplies, host cables and video adapters in the total purchase cost.

Troubleshoot before replacing

Try one known-good display path and then add the second screen. If the issue follows one cable or input, buying a new dock may leave the cause unchanged. Start with a missing-picture check or check slow charging.