It´s a problem of cable. Anyway, signal from pci-e will not survive in unshielded cables. EMI generates by psu, cables and so on will penetrate unshielded cable and thats it.
You need to use a very good cable. I am using 100cm and is it ok, but this will be almost the limit.... I am sure that more than 150cm will be almost imposible...
Thanks for your answer.
I bought here :
https://www.amazon.com/dp/B01CPZHPYG?ref_=pe_2640190_255746880_404_E_DDE_dt_1It's unshielded ??
Any link, otherwise, of 90cm+ very good cable ?