Question Asus sabertooth x79 pcie x1

[Sunnyoil]

Hi people new here, Im minning for few months and i got myself 2nd rx 5700xt ready to join the crew but problem is when i connect raiser to pcie x1 the windows won't boot and i get csm bios message. Risers are 009 and are working fine. Everything is set on legacy first, gen 2. Only pcie x1 setting i have is to change from auto to sata6g. When it's on sata6g it boots the windows but there is no 4th gpu in device menager or amd adrenaline. Mobo is asus sabertooth x79 with 2x rx580 8gb and one rx5700 psu is corsair rm850w Bios is updated to 4701 (4801 is for 128gb ram support only) So can some good soul help me get trough it? Thanks 😊

 

[Lutfij]

You will need at least a 1.2KW PSU for those 4 cards.

 

[Sunnyoil]

580s are using 180 and 5700 is using 144w..i tried with 580 4gb but it just wont boot windows and i dont have 4g decoding in bios