I'm hoping someone can help me, I bought a fully assembled ETH miner with 6x AMD 290/380 4GB gfx cards. The rig was happily mining at a steady 120mh/s for a year and then things started acting up. First thing that happened was one of the cards suddenly started reported ~2.x mh/s rather than the normal 20mh/s, knocking the power down to a total ~100mh/s. I wasn't too worried about this, so i just let it keep hashing away. It was when a second card failed, this time reporting 0 mh/s that I decided it was time to fix things.
So I picked up 3 matching gently used 290/380 4GB cards for a decent price and swapped out the 2 cards that were producing <20mh/s with new cards. This did nothing to solve the problem. I asked around on slack and some people suggested I swap out the cheap "ribbon risers" with "proper risers" so I did that, also did nothing to solve the problem.
So now I'm here seeing if some pros can help me out. The weird twist to this situation is that with all 6 cards in the rig, including the one that is under-hashing, I can get a total ~104mh/s. I don't know if these operate in pairs or something but if I disconnect the 1 card that is under-hashing, the entire rig drops down to 80mh/s with a DIFFERENT card now under-hashing- I'm completely baffled by this; put back the "slow" card and its back to an almost-full-power ~104mh/s.
So I now have 9 of these higher-end gfx cards but for the life of me can't figure out why I can't get that last 20mh/s of power back. Is it possible the PCI port labeled #1 in the pics is just like... dead or something? Is there anyway to test that? Any help or guidance at all would be appreciated, TIA!
Top view of rig, you can see the "under-hashing" card as the fans don't need to be running often at 2mh/s!
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fdl.dropboxusercontent.com%2Fu%2F25508862%2FBCT%2Feth_miner%2Ftopview_running_labeled.jpg&t=665&c=G0Tv-QVHSYh7vA)
Bottom view of the rig, shows the USBs connected to the "better risers". Red indicates connection to the "under-hashing" card.
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fdl.dropboxusercontent.com%2Fu%2F25508862%2FBCT%2Feth_miner%2Feth_miner_bottom.jpg&t=665&c=Fdl71wv5oR4ASA)
Mining console, using Claymore dual miner in ETH-only mode. Changing the mining software has ZERO impact on the hashing results. Note GPU0!?
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fdl.dropboxusercontent.com%2Fu%2F25508862%2FBCT%2Feth_miner%2Feth_miner_console.jpg&t=665&c=p0sbx3l6fSOPTw)
The "extra gear" I've gone thru/blown $$ on trying to get that 20mh/s back!
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fdl.dropboxusercontent.com%2Fu%2F25508862%2FBCT%2Feth_miner%2Feth_miner_gear.jpg&t=665&c=E5fzIBtW_bC00g)
Thanks again in advance for any help, really stumped here and tired of wasting time+$$$ on things that don't work!
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)