R9 280X drops in Hashrate after 4 GPU's

Hello fellow miners …

I saw the other thread but the answer is not answered.

I have 8 R9 280X cards and an Asrock H110 PRO BTC.

I have 2 power supplies with 1800 watt in total.

With 4 cards i gor about 1100 Sols and after putting in the 5th card i got 150 sols per card.

tried overclock but there is no change.

I use simpleminingOS because this setup with Windows is giving problems.

Who can help me.

Thanks in advance

Greetings Justbitcoinz

The cards went from 250 - 270 a card with 4 and 130 - 150 with one card more … Somebody know ?

Are they all the same card or set to same clocks?


Can you detail what BIOS changes, if any, you have already made? My first suspicion is that you may need to adjust the PCI max speed to a lower generation setting, but I’d like to know what you’ve done already.