What's wrong with my pc build?

Hello there, I just started to play a bit with U4 but something is not working well.
When I go “Play Mode” the movements are scattered and the lights are not working properly.

I guess there’s something old on my pc setup that I have to change but I can’t focus on what exactly is.
The pc is old but I can’t manage to change everything now, so I have to do that step by step, starting by the oldest thing I have.

Those are the components:

Processor: Intel Xeon W3530 2.80 GHz
Graphics: NVidia Quadro FX4800
RAM: 12Gb

The graphics card is by far your most limiting component. But I’m not sure that the outright errors are because of it. Your other components are at least a bit above the minimum recommended specs.

My recommendation is to get a GTX 970 card or faster to start with.

Sure its a nice thing a 970 but i run a 560ti on an i 2500k with 8 GB ram and even with that you can do nice stuff with UE.

Neither your CPU or GPU are intended for gaming, which may explain why it is not running so well. You’ll want to upgrade both of those (GPU mainly) if you are looking for good performance in UE4.