Gpu disconnects when the case is put on its stand.

So I have got two computers both identical and I have just got two new monitors. So the first one is fine, but the gpu in the second one disconnects when the case is put on its side.

The case is a thermaltake tower 300 and the gpu is a 9070 nitro.

I had this issue a few days ago and fixed it by reseating the gpu but this time I can only get the gpu to output a signal when the case is upright and not on its stand.

If I have the pc running and rotate it careful to how it would be on the stand it just disconnects.

It sounds to me like a loose connection but I have reseated the gpu so many times but it just isn't having it .

Does anybody have any advice or tips ? Im at a loss at the moment and im not sure what to do.

Thanks