Quote from: adaseb on April 03, 2016, 01:02:49 AM

The problem with undervolting is that it might crash every few hours or so. And you have to manually restart the mining.

Got 96 nano's running for weeks with my rom. No issues. The issues start when i go lower than -125mV.

Believe me, you can't imagine how much testing i've done...

Quote from: Ayers on April 03, 2016, 07:48:20 AM

not to mention removing the warranty with all those bios flash, i would certainly not do it with so many gpu, the risk to screw one is high, and those card are expensive, it must be said that without this mod, having 1500w for 170 mega on ETH, is not good at all, a 970 can do 1k and 132 mega, this is almost 200 mega with 1500w

Well, you've got a point there. But like i've said, secondary bios switch. The risk to screw one isn't "that" high. If you go to low on the volts it will just crash the display driver and reset itself. So no risk there.
If you "OVER"volt, then yeah, you could risk screwing it up.

170Mh/s, 6cards, 1500watt, true. Those cards are getting pushed, i haven't mentioned that i upped the Powertune to 50 which will also consume some extra energy.
Bumping the cards from 1000 core clock to 1050 core clock will gain you an easy 10Mh/s at only 60-70 watt extra (Complete rig)

Again, my power draw is all from the wall. So Motherboard, cpu, Memory, 6 cards that have to get power, 6 risers that all need some power.

If i do this test on 1 card, directly seated into the PCI slot (which i have done) the power draw is A LOT less.

I haven't really calculated on this to happen either. But it's still okay

Quote from: Batelk on April 03, 2016, 08:16:53 AM

Thanks for the good efforts.
So the memory consumes very little energy. With -100mV, power drops from 1100 to 1055W.

Yes indeed, it didn't drop very hard.
Although. When using a stress program like 3DMark the memory controller will be using A LOT more of energy, because basically the memory will be used :p

When mining Ethereum, or any other algo, the memory on Fiji isn't really being used at it's fullest. Well, Almost not.

So cranking that down to -100mV was basically logical for me to do as it's not needed.

(-100mV will still be perfect for the HBM mem to run on 500clock at full load) "Stress test in 3DMark".

Quote from: glerand on April 03, 2016, 08:20:56 AM

Is there R9 390 mod? The default memory speed is 1500 MHz, but we only need 1250 to mine Ethereum. So memory voltage mod is useful.

You could create one

I believe there are plenty of Hawaii tutorials out there :p

if you have questions, just ask, no worries!

Quote from: bobben2 on April 03, 2016, 08:27:36 AM

Eliovp,
Excellent initiative, albeit a risky one. Those cards cost around $500-520 each?

Would you happen to know how to undervolt an R9 380X by BIOS mod?
I tried the Hedzin BIOS reader, but that didnt work on on my card.

Thx!
Well i got a nice discount because i bought in bulk :p

Well, it's probably the same as like i've done.
Just different numbers.

I believe i have seen an Hawaii Bios Editor somewhere. Just don't know where. So that could be easy to do.

Dunno for Tonga though.