If you are building your own, you are likely looking at one of these common interfaces: ADT-Link R43SG (M.2 NVMe):
For a detailed step-by-step guide and troubleshooting, the most authoritative community is diy egpu setup skacat-
A DIY eGPU setup boosts laptop graphical performance by connecting a desktop GPU via adapters like EXP GDC Beast, Oculink, or M.2 NVMe, often requiring an external monitor and ATX power supply . Proper implementation involves hardware connection via Mini PCIe/ExpressCard/M.2, installing GPU drivers, and, if necessary, using specialized software for Error 43, notes MakeUseOf and YouTube . If you are building your own, you are