3rd gpu makes computer extremely erratic

[SkylerSutton]

I've got a computer with two 8gb rx580s in it and it runs perfectly fine but I'm trying to add an 8gb rx570 which gives me all kinds of problems. Firstly windows 10 takes close to 5 minutes to start, then every program except for nicehash takes an additional minute or two to open and just as long to register any changes I make within the programs, but if I wait for everything to register ultimately it works. The real problem starts when I try mining with them, maybe the first 30 minutes goes smoothly but then both of my rx580s stop functioning and will not start again unless I reboot the computer, however the rx570 still works. All of the cards individually work fine and power isn't an issue, whatever is happening seems to be only when I plug in the third gpu. Beyond that I'm clueless if anybody has an idea I'd love to hear it.

[Heliian]

Well the problem is with the 3rdth gpu I think. 

 

Try all combinations of 2 GPUs and see if it works. 

 

More specs are needed, it's possible that the system is being overwhelmed with the lanes used, did you try manually configuring/restricting in bios?