The dreaded 5th gpu debacle..

I know that this has been addressed many times but there’s a lot of info to sift through that hasn’t helped me so far so please bare with me.

Specs asus prime z270-a mobo 4- 6700 xt 1-6800 Two evga psu 750, 850 linked with add2psu I5 5400 cpu And I am running of a 500gb m.2 I had lying around (thinking this may be my culprit?)

I have it running with 4 gpu fine and stable I added the 6800 and it turns on and fans spin but no detection. I unplugged all but the 6800 and I get detection. I have 4g enabled gen 2 speeds and spectrum clocking disabled.

I switch around the order in which they are connected to the mobo and started getting issues with pc booting but not passed the bios screen( tv said hdmi not present) put everything back to how I had it so back at square one but if anyone knows how I can get the 6800 to run and get detected I’d much appreciate it!