Impressive 5870 efficiency

[johnyj]

I tried to undervolt it to the middle voltage setting, which is 1.063 volt, but surprisingly found out this card can still run stable at 880 Mhz, it became much cooler, and still generate 400Mh/s, total card power draw is only 137W, which brings a 2.92Mhs/J performance, really nice!

[kliffen]

That's awesome! How long have you been running it like that for?

What's your memory clock?

[Mousepotato]

See if your card can go down to 900mv @ around 820-830MHz.  You'll get around 375-380 MH/s and power draw should be even lower (well worth the 20-25 MH/s you're giving up).

[TheHarbinger]

*cough*

Been running 5 5870's at 1.000v, 800/150MHz for a little over 1.8GH/s at 600W.   

3 MH/W   

[johnyj]

I'm still testing, if I get enough data sample, I may compile the result to a chart.  Another 5870 barely make 830 Mhz under 1.06v setting, anything higher than that will cause a hard hang, it's also luck related

The voltage only have 3 states: either 1.163V, 1.063V or 0.95V, other voltage settings seems make no difference in power usage measured. Under the same voltage, higher GPU clock always bring better Mhs/J, maybe 0.95v is even better, and that will prolong the life for the card too

[Mousepotato]

The voltage only have 3 states: either 1.163V, 1.063V or 0.95V, other voltage settings seems make no difference in power usage measured. Under the same voltage, higher GPU clock always bring better Mhs/J, maybe 0.95v is even better, and that will prolong the life for the card too

Are you using the ATI GPU Clock Tool?  IIRC that one only gives you a few choices, via drop-down menu, for voltage settings.  If you switch to Trixx or MSI Afterburner, you can key in whatever voltage you want.

[DeathAndTaxes]

The voltage only have 3 states: either 1.163V, 1.063V or 0.95V, other voltage settings seems make no difference in power usage measured. Under the same voltage, higher GPU clock always bring better Mhs/J, maybe 0.95v is even better, and that will prolong the life for the card too

Are you using the ATI GPU Clock Tool?  IIRC that one only gives you a few choices, via drop-down menu, for voltage settings.  If you switch to Trixx or MSI Afterburner, you can key in whatever voltage you want.

or cgminer.

[johnyj]

I'm using AMDoverdrivectrl, I can put in any voltage precisely up to 0.01 V, but the read out on my power meter only jumps between 3 stage: 0.95 V; anything between 0.96V and 1.06V; and anything above 1.07V. The difference in power consumption is about 10% each stage

After some test yesterday, I found the most feasible choice is voltage in the second stage (e.g. 0.96v ~ 1.06v) , here the power consumption dropped more than 10% and the card can still run at stock clock or even higher with lowered memory clock, cooling is much easier. The lowest stage can bring down the power consumption 10% more, but that will cause the card to be too underutilized, does not worth the investment

[italeffect]

I have 2 5870's.
One is stable at 840/180 1.02v 384 mh/s
The other is stable at 850/180 1.0v 390 mh/s