Why my 3090s are so weird... I can't find any hints from the internet, please help

[superdick0]

When my rig run with 1x3060ti, 1x3080, 1x3090, the power consumption and hashrate are very stable.
When I try to add another 3090 into the rig, then either one 3090 (random) will become unstable, the power consumption and hasdrate will keep dropping
Working fine at the beginning, both cards are running with 325w + 126mh

Then keep dropping until below 300W…

I have tried below:

1. replaced the power cables
2. changed to different pcie slot
3. added one more psu to make sure the power is enough (tried 1200w and 1750w)
4. removed the 3060ti and 3080, but the issue still happen for those 2x3090
5. no matter how i raise the PL, mem clock or core clock, but it won’t change anything on the hashrate or power…
6. if i lower the PL, mem clock, it does lower the hashrate and power
7. this issue only happen on the 3090, but not others
8. tried to use phoenixmine, lolminer, t-rex, but no luck
9. tried to mine different type of coins, BNB, ETH, TR, no luck
10. both cards are new (inno3d 3090 x4)

hope someone can help, million thanks.

[Lorenz29]

Hey Superdick,

I’m running 5x 3090 and I believe your cards are thermal throttling (vrams). By lowering the wattage it’s the way that the card uses to cool down the memories.

Try to move the wattage capped one out of the rig. In someplace where don’t receive the hot air of the others and see if with that is better.

With all the tests you did, I suppose you are connecting each card with 2x 12v cables each.

Regards,

[Lorenz29]

Also I improved wattage, hashrate and temperature by using Absolute Core Clock instead of Offset:

[crosswindjones]

I have been fighting with a 3090 too… In a test rig it ran perfectly silent for weeks but when I placed it in a large rig it throttles non-stop. I agree with this recommendation, likely hot air from the backplane of another card is being sucked into the and through the 3090 causing addl. heat issues. Then again my still throttles without a card in front of it in the same HOS rig so I have not found a real solution myself.