New graphics card won't work but old one works fine

Drew2323

Commendable
Sep 14, 2016
3
0
1,510
I have a Intel® Desktop Board D5400XS with 2 Intel core 2 extreme CPU x9775 with 8gb RAM. I got it from someone who was running two 970's on it for gaming. He took the power supply, Graphics cards and hard drive out and gave it to me. I've put in a samsung 250gb ssd, 750w power supply and i had purchased a radeon rx 480 to put in it. I could not get it to post with the 480 so i popped in a spare radeon HD 6670 and got it to post and loaded the operating system (win 10). Computer works fine with that card but still wont post with the 480. I've tried just about evey thing i can think. With the 480 i get a 5A error and cant get into bios. Manual says thats resetting the pata/sata bus and all devices. Which from what ive read is just unplug everything and plug back in...did that. No luck. I returned the graphics card for a new one in case it was just a bad card and same thing. Finally i returned the 480 again and ordered the nvidia 1060 thinking maybe it just didn't like the 480. This is my first build so any help would be great. I don't know all that much, friends who do are cant figure it out. Could it be an issue with the older motherboard compatible with new graphics?