Secondary PSU Issues

[Swimmer63]

I am trying to add a second PSU to a rig. I have the first one running the motherboard and 3 GPU's. One is 390 that is recognized as 2 gpu's so really the system sees 4 gpu's total but it's 3 physical gpu's. But I am trying to add another gpu and need a second psu to do that.

I added another gpu with a powered ribbon cable and a 2nd psu. I have one of those 24pin red on/off switches that I am using rather than a paperclip or wire. But that should not be an issue.

I turn on the secondary psu and then the primary. The fans run on the 4th GPU, but it does not get recognized by the pc (windows 7) or the miner (claymore) and it does not mine. It stays very cool like it's not working at all.

I have tried two different gpu's as my 4th to see if it was a gpu problem. But it's does not appear to be. Neither gets recognized by the pc.

Any thoughts?

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[philipma1957]

so is it 5 gpus but four slots??

you have a dual gpu?

what is the mobo

do you know the ribbon is good?


you could try the delete amd driver boot

install AMD driver  boot

see if it shows up

[Swimmer63]

It's a gigabyte ga-990fxa-ud5 on Win 7.
Reading some other threads I think 4 GPU's may be the max for Win 7.  Some other miners upgraded to Win 10 and now they can get 6 GPU's on the board.  I am in the process of trying the same.