TL;DR: NVIDIA's RTX 5090 graphics card requires 4 x 8-pin connectors for 600W power officially, but can operate with 3 x 8-pin connectors at 450W, seemingly running only 5% slower in 4K benchmarks.
All the connectors are orientated in the same way as those on the Amstrad motherboard. I.e. the pin(s) towards the top of rear of the keyboard PCB are those towards the rear of the motherboard PCB and ...
This prototype interface replaces traditional 24-pin ATX and 8-pin EPS power connectors, as well as 16-pin connectors being fed into higher-end GPUs like the NVIDIA GeForce RTX 40 series ...