I have only one pci-e lane but i've been thinking if the lane is broken because my older gpu, which is not broken, doesn't work there either
i noticed that some red light appears on the gpu on startup, it has a number 1601 or something. It's somekind of a critical temperature light but could it be caused by something else?
hmmm.... well if your other GPU worked before but doesn't now then the PCI-E lane could be damaged/faulty.
I'd test the card in another PC if possible as that red light doesn't look promising.
You just need to narrow down what could be the problem, at the moment it could be the GPU or motherboard, hence the need to test in another PC.