Where has my hashrate gone?

[Amstellodamois]

Ever since I started with my rig building, all my RX 580 have been able to achieve over 31 MH easily.
Yesterday, I had four (2 on the motherboard, two on risers) running at 31.6 MH.

Today, I finally received my frame, build it with 6 risers and the hashrate has dropped for most cards (5 out of 6) as you can see here:

https://image.ibb.co/dmtfmw/Capture_d_cran_2018_01_26_19_02_30.png


I'm using the latest AMD drivers, all their BIOS have been flashed, they're all set to "compute" in the AMD settings and the clocks and voltage are the same for all card. I restarted the miner with the same result (5 slow, 1 fast).

The virtual memory is set at 16 MB.

I thought it could be the power supply but I'm using only 850W out ot 1000W.



In short, I'm puzzled. Has anyone an explanation?

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[xxcsu]

I thought it could be the power supply but I'm using only 850W out ot 1000W.

how did you come up with that number ? 850 Watts ?
that 850 watts at the wall or any kind of software telling you that 850 watts ?

[Dtrucksguitarfan]

A 1000w power supply does not deliver 1000w to your rig.  A GOLD rated power supply will deliver 80% of the 'max wall draw' of 1000w in this case, which means 800w to your rig. 

It sounds like you were running fine on 4 cards, now you are  running 6. You have drastically increased the power draw and your power supply cant keep up.

[MrTDHP]

A 1000w power supply does not deliver 1000w to your rig.  A GOLD rated power supply will deliver 80% of the 'max wall draw' of 1000w in this case, which means 800w to your rig.  

It sounds like you were running fine on 4 cards, now you are  running 6. You have drastically increased the power draw and your power supply cant keep up.

Wrong.
A 1000w power supply DOES (is able to) deliver up to +/-1000w. A 80Plus rated (80% efficiency) will draw 1250w from the wall if it is used at max. A 80Plus Gold will have a higher efficiency thus drawing less from the wall for the same output

[Dtrucksguitarfan]

A 1000w power supply does not deliver 1000w to your rig.  A GOLD rated power supply will deliver 80% of the 'max wall draw' of 1000w in this case, which means 800w to your rig.  

It sounds like you were running fine on 4 cards, now you are  running 6. You have drastically increased the power draw and your power supply cant keep up.

Wrong.
A 1000w power supply DOES (is able to) deliver up to +/-1000w. A 80Plus rated (80% efficiency) will draw 1250w from the wall if it is used at max. A 80Plus Gold will have a higher efficiency thus drawing less from the wall for the same output

thanks, i had it backward.

[Wipro]

A 1000w power supply does not deliver 1000w to your rig.  A GOLD rated power supply will deliver 80% of the 'max wall draw' of 1000w in this case, which means 800w to your rig. 

It sounds like you were running fine on 4 cards, now you are  running 6. You have drastically increased the power draw and your power supply cant keep up.

Who said this not enough for the 4 cards with the motherboard. Rx 470, 570 and 580 takes mostly 200 watts per card. Including the electricity consumption of motherboard this is far enough buddy. For 6 cards rig 1200 Corsair would be fine option not more than this number you said. I see people complaint about the cable sticking issue while adding more number cards to rig than allotted but for supply it is enough still.

[Amstellodamois]

About the power draw:
1. It's 850 W from the wall (a smart plug is telling me this)
2. If I launch the miner with two cards (for instance), I still get around 28 MH

[Amstellodamois]

I think I've found a lead.

I've used OverdriveNTool to set the memory clock and voltages and I think the values don't register like they should, so some cards are running at 2000 MHz, others at 2250.

[Set Ready Go]

I think I've found a lead.

I've used OverdriveNTool to set the memory clock and voltages and I think the values don't register like they should, so some cards are running at 2000 MHz, others at 2250.

Try set the  OC in Wattman then , easier nowadays when you can save profiles there aswell.

[Amstellodamois]

I hate wattman. It is sooooooo slow and buggy :-(