Undervolting a 5870 at 0.95v

[jamesg]

Hello fellow bitcoiners,

I have seen and used undervolt settings at both 1.0v and 0.9v for my 5970s. I have not however been able to find anyone who is running with the voltage at 0.95v.

Anyone doing this?

Thanks,
gigavps

P.S. You can see all of my undervolt settings here -> http://farm.gigamining.com/mgpumon/

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[mitak64]

My 5870s run at 810core/275mem @1.00V fine.
Tonight I'll try 0.95 as well.

[Gomeler]

I have only been running my 5870/5850 that support undervolting at 1.0v at 850/200.

Your BFL Single rig is equal to my GPU farm 

[JWU42]

I have yet to devolt the 5870s.  They are able to stay cool enough without the fans running beyond 50%.

My go to for 5970's has been 755/180 @ .99v and curious to hear others comments on a slight OC with lower than 1.162V on their 5870s.

[rograz]

got 2 xfx ref cards running 0.95V at 710/730MHz pulling around 75-80W per card from the wall (80+ bronze psu) I just wish all my non ref cards would do 0.95V as well, :/

[Mousepotato]

What kind of MH/s are you guys getting at these underclock/undervolt settings?

[rograz]

The average for me running 0.95V is around 310 MH/s for my 5870s and around 290 MH/s for my 5850s. Each card was tested individually and they range from 680 Mhz to 740 Mhz for what they can handle with most of them just around 700ish.

[jamesg]

The average for me running 0.95V is around 310 MH/s for my 5870s and around 290 MH/s for my 5850s. Each card was tested individually and they range from 680 Mhz to 740 Mhz for what they can handle with most of them just around 700ish.

Good info. Thanks for posting.

[italeffect]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 400, otherwise it crashes.
The 2nd card is happy as can be at .95v

[jamesg]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 40o, otherwise it crashes.
The 2nd card is happy as can be at .95v

I like the 750/150 at the .95v! 

I'll have to try that out in a little while.

[jamesg]

Your BFL Single rig is equal to my GPU farm 

Those are my hash monsters! 

Best thing about them is that they never crash. They just keep on hashing.

[Mousepotato]

I like the 750/150 at the .95v!  

I'll have to try that out in a little while.

Yeah that sounds like a pretty good cruising speed.  I wonder if these can be volted down any further?  On 5970s you can go down to .90v (610/200) for 550 MH/s, and possibly even lower on the voltage (in the .86-.88v range).  Has anybody had any luck with sub-.95v on 5870s?

[jamesg]

Yeah that sounds like a pretty good cruising speed.  I wonder if these can be volted down any further?  On 5970s you can go down to .90v (610/200) for 550 MH/s, and possibly even lower on the voltage (in the .86-.88v range).  Has anybody had any luck with sub-.95v on 5870s?

I run my 5870s at 650/150/.899v currently for around 295Mh/s.

I tried the 750/150/.95v on a 5x5870 rig and things crashed before they even got started.

[ARapalo]

How much electricity are you really saving with this undervolting?

[zvs]

i suspect there's a point where the diminishing returns become potential profit lost w/ huge undervolting.

right now i have a 5870 running at 1000/300, 1.05v, getting around 460mhash/s

two others are at 980/215, ~1.14v (I forget exactly), getting around 440mhash/s.  In about 5 or 6 hrs here, I'll drop them to 850/215 @ 1.02v... the other one, I just leave at 1000/300 as it never goes above 65oC anyway

(ed: oh, my elec is only 8c per kwh.. i wouldn't undervolt at all except for the heat issue during the day.  still working on an outdoor workshop area to put them in)

[chiropteran]

I've done similar with 5830's

One pair is seemingly stable at C=765  M=200 V=950, putting out 235mhash each

The other pair is is only stable up to C=750 at V=950, for 220mhash per card.

I actually running them at C=870 M=300 V=1050 for now, which is 262mhash per card.

Don't have my watt-meter here today so I can't really say which voltage is more efficient overall.

[Zubilica]

Yeah that sounds like a pretty good cruising speed.  I wonder if these can be volted down any further?  On 5970s you can go down to .90v (610/200) for 550 MH/s, and possibly even lower on the voltage (in the .86-.88v range).  Has anybody had any luck with sub-.95v on 5870s?

I run my 5870s at 650/150/.899v currently for around 295Mh/s.

I tried the 750/150/.95v on a 5x5870 rig and things crashed before they even got started.

Try 775/290/0.96v

[jjshabadoo]

On another note, I get 900 engine, 300 mem at 1.125 but I know plenty of people have posted those numbers. I get about 410-420 mhash, but I use an old version of cgminer because those rigs are linuxcoin and I'm afraid to F with them..lol.

I'll need to under volt soon, so I'll post what I get after this weekend.

[jamesg]

Ok miners. I have been doing some testing of my own and I think I have found some more optimal settings.

Before I was running:

650/150/.899v @ 291Mh/s each and 1455Mh/s total

I am now running two 5x5870 rigs at:

800/150/.959v @ 367Mh/s each and 1835Mh/s total

Looks like the .959v setting is the closest to the .95v I was after and am still able to get the 800 core clock. I am also getting 380Mh/s more out of each rig with these settings which is pretty sweet considering the low voltage.

Try it out and let me know if it works for you.

[Cablez]

Hey gigavps,   what kind of savings do you get from the rig going from same clocks at stock to the new .95V?  Is there a substantial wattage savings?

I am thinking of starting to undervolt my rigs as electricity is killer but stability is real concern. 

[jamesg]

Hey gigavps,   what kind of savings do you get from the rig going from same clocks at stock to the new .95V?  Is there a substantial wattage savings?

I am thinking of starting to undervolt my rigs as electricity is killer but stability is real concern. 

Not sure to be honest. I don't have a kilawatt that works on 208v. My main concern with undervolting is better stability and longevity of the cards. Also seeing a decrease in my power bill is nice.

[rograz]

Power draw increases exponentially with voltage so even a seemingly small decrease of 0.1 can be quite a big efficiency increase. The reduced frequency the cards can handle with the new voltage often follow a more linear scale.

[Littleshop]

Yeah that sounds like a pretty good cruising speed.  I wonder if these can be volted down any further?  On 5970s you can go down to .90v (610/200) for 550 MH/s, and possibly even lower on the voltage (in the .86-.88v range).  Has anybody had any luck with sub-.95v on 5870s?

I run my 5870s at 650/150/.899v currently for around 295Mh/s.

I tried the 750/150/.95v on a 5x5870 rig and things crashed before they even got started.

About 1/2 my cards can take 700/150/.95v

I use this as my 'summer' setting for some of my miners.

[johnyj]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 400, otherwise it crashes.
The 2nd card is happy as can be at .95v

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

But of course if you have plenty of hash power and want to reduce the noise/heat, it will help

[TheHarbinger]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 400, otherwise it crashes.
The 2nd card is happy as can be at .95v

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

But of course if you have plenty of hash power and want to reduce the noise/heat, it will help

All my 5870's are set at 1.000v and 825/150 clocks.  So each rig (5 cards) gets about 1850Mh/s @ 650W.

[jamesg]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 400, otherwise it crashes.
The 2nd card is happy as can be at .95v

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

But of course if you have plenty of hash power and want to reduce the noise/heat, it will help

All my 5870's are set at 1.000v and 825/150 clocks.  So each rig (5 cards) gets about 1850Mh/s @ 650W.

Do you mind running a rig at 800/150/.959v as seeing what kind of power draw your are getting?

[TheHarbinger]

I have 2 under-volted 5870's.

One at 840/155 and 1v = 384 mh/s
The other at 755/155 and .95v = 347 mh/s

If I try to set the first card to .95v I have to set the engine clock too low to around 400, otherwise it crashes.
The 2nd card is happy as can be at .95v

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

But of course if you have plenty of hash power and want to reduce the noise/heat, it will help

All my 5870's are set at 1.000v and 825/150 clocks.  So each rig (5 cards) gets about 1850Mh/s @ 650W.

Do you mind running a rig at 800/150/.959v as seeing what kind of power draw your are getting?

Can't really do it, since I have a mix of different vendor cards on each rig and they are running headless.  Well, I mean technically, I could do it, but the thought of taking a rig off line to intentionally make it unstable for testing, isn't very appealing to me.  Every card I have seems to be happy at 1.000v and 825/150 clocks.  I'm sure some could go to higher clocks and/or lower voltage, but I'm not going to muck with them just to squeeze out another 20Mh/s or save another 10 watts. 

[johnyj]

On 5870, there are only 3 effective voltage, distributed in range:

0.95v
0.96v-1.06v
1.07v-1.17v

0.96v and 1.06v actually gave same readout on power meter, so you may run 825Mhz on 0.96v, but that will not improve efficiency

[Gomeler]

Anyone take a multimeter to their cards to see how fine-tuned the voltage steps are? I know Afterburner is accurate on 5870s(I measured it back in the day, it is good up to 1.55vgpu on the 5870). But, I'm not sure how cgminer adjusts voltages and if it is as accurate.

[italeffect]

On 5870, there are only 3 effective voltage, distributed in range:

0.95v
0.96v-1.06v
1.07v-1.17v

0.96v and 1.06v actually gave same readout on power meter, so you may run 825Mhz on 0.96v, but that will not improve efficiency

I have found the same thing measuring wattage at the wall. (except I thought there was a step in there at 1v as well) You always want to be at the highest voltage in the bracket and whatever the highest clocks that will support.

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

I didn't include the wattage so you can't draw that conclusion. I don't have the per-card wattages at the wall (cause I don't feel like interrupting mining to measure) but based on extensive earlier testing dropping to 1v and .95v on some cards I'm up to about 2.85 mh/s per watt, vs. earlier at 2.3, 2.5 per watt etc.

(1 rig = 1x 6950 unlocked, 1x 5970, 2x 5870 = 1767 mh/s @ 619 watts) And the "efficiency" could actually be much higher except for that 6950 is at stock voltage. As soon as I flash the bios and undervolt it the total should be even better.

If you are concerned about power usage like I am, it certainly makes sense to undervolt.
If the rig ever hangs and I have to reboot it maybe I'll measure the wattage on the individual cards at stock and undervolted to provide the hard numbers.

[jamesg]

Well this is interesting. I have two 5870s on miner100. I set them to run at 800/150/.959v but for some reason they are running at 850 core!

http://gigamining.com/mgpumon/

Anyone know why that would happen? Or better yet, I'm wondering if I can run all my 5870s at 850/150/.959v.   

[rograz]

That's a 5% drop in power usage and 10% drop in hash rate, not very attractive IMO

1v to 0,95v is not a 5% reduction in power usage, it's not linear it's exponential.

[zvs]

On 5870, there are only 3 effective voltage, distributed in range:

0.95v
0.96v-1.06v
1.07v-1.17v

0.96v and 1.06v actually gave same readout on power meter, so you may run 825Mhz on 0.96v, but that will not improve efficiency

it'd make the card run hotter, so the fans would spin faster?

so it would improve efficiency by reducing wear & tear on the card, fans, and whatever watts the fans take from spinning faster

[rograz]

2 ASUS EAH5870 V2 1gb cards i've got doesn't seem to be able to set anything below 1,06V for me, anyone else who got experience with undervolting these cards? Else I I'll just have to add them to the rigs I plan to take down when profitability goes down I guess :/

[Grinder]

Anyone know why that would happen? Or better yet, I'm wondering if I can run all my 5870s at 850/150/.959v.   

I doubt those read outs are correct. I have not been able to run any 5850, 5870 or 5970 GPUs reliably at more than 750 MHz at 0.95v, and 780 MHz at 0.97v.

[rograz]

Agreed Grinder, not a single one of 15 my cards running at 0,95V can do above 740 24/7 stable so it would either have to be one crazy bin or the card simply isn't running at that voltage.

What happens with the 5xxx card's is that if you set a voltage the card can't handle it will default to the next step above it or the stock voltage in some cases. At least this is how all of my cards seems to behave (hard to tell since some non ref boards doesn't support voltage monitoring in gpu-z)

Like the Asus boards I just mentioned a few posts earlier, they are both flashed to 0,95 but draw exactly as much and clock as high as when I undervolted them in windows to 1,06V.

[jamesg]

Agreed Grinder, not a single one of 15 my cards running at 0,95V can do above 740 24/7 stable so it would either have to be one crazy bin or the card simply isn't running at that voltage.

I now have 10 cards running 850/150/.959v! Two are running 825/150/.959v.

http://gigamining.com/mgpumon/

See rigs 100, 107 and 110. The 110 rigs has 5k shares on each card.

I think the .959v over .95v makes a big difference.

[this time]

It is possible to run a 5870 at 850/150/.95 but unusual. I have one that will do it. I've also had them that won't do 850 on anything less than 1.100. And if you got the 5870 cards from bens bargains they won't underclock well in my experience.

You have to always check with a kill a watt to make sure that the readings you are getting are actually dropping the power consumption. The software readouts are not always accurate in any of the programs, including gpuz. And if you have a serious farm it may not be worth going through every card and figuring out what it will do.

[DeathAndTaxes]

VRM are only capable of certain discrete voltage values.

So if 0.959v isn't a valid voltage the card will actually be running at voltage > 0.959V whatever the next higher step is.  Which according to johnyj (not verified by me) is 1.06V

So 0.959V, 0.96V 1.0V, 1.0123456789V it doesn't matter the card is running at the next higher valid step which may be 1.06V.

The only way to verify for sure is to pick a static clock (lower is better) and connect rig to watt meter (like kill-a-watt).  Change voltage and look for a change in wattage.  No change in wattage = no actual change in voltage.  Since wattage is going to have some variance anyways it may require measuring power instead (kWh) and time to get average wattage.

So something like

Set clocks to a static 700 Mhz.
Set voltage to stock.
Measure power for ~10 minutes. 
Divide power by exact time to get avg wattage.
Lower voltage and try again.

You will notice something like this

Voltage: 1.05V, 1.04V, 1.03V, 1.02V 1.01V = same wattage.  Then at some point the wattage will drop.  THAT IS THE DISCRETE STEP.

[rograz]

Was gonna post but D&T pretty much got it all and then some :p

[Gomeler]

Not sure why you guys are dicking around with trying to determine voltage by watching the power draw. Whip out a multimeter and dispel all uncertainty.

[TheHarbinger]

Not sure why you guys are dicking around with trying to determine voltage by watching the power draw. Whip out a multimeter and dispel all uncertainty.

Probably because nobody feels like destroying their card by trying to probe a BGA mounted GPU.

[Gomeler]

Not sure why you guys are dicking around with trying to determine voltage by watching the power draw. Whip out a multimeter and dispel all uncertainty.

Probably because nobody feels like destroying their card by trying to probe a BGA mounted GPU.

I see you've never looked at a GPU before. The SMT caps on the back of the GPU supply the voltage you guys are all talking about. One side is ground, the other side is vddc. Not even sure why the GPU being a BGA package comes in to play here.

If your card doesn't have a backplate you can also measure from the vddc output capacitors. Next weekend when I consolidate my 5870s I'll try to remember to probe some of them while playing w/ voltage settings.

[superfastkyle]

I got some 5870's today, a his reference and a non-reference. Been playing with the settings listed here. No crashes at 0.959 volts, but even though I have core at 850 and get almost 400 reported mhash it appears to produce less shares then when I put them at 1.02v and the same speeds, which has been my go to setting for 5970's. It shouldn't take more than 10-15min to throw luck out of the equation as far as shares are concerned right? Does anyone else notice the same thing?

this is going by the share/minute average in cgminer, maybe this isnt even accurate who knows?

[Beaflag VonRathburg]

On 5870, there are only 3 effective voltage, distributed in range:

0.95v
0.96v-1.06v
1.07v-1.17v

0.96v and 1.06v actually gave same readout on power meter, so you may run 825Mhz on 0.96v, but that will not improve efficiency

That would explain a lot. I have two 4x5870 rigs that have the exact same parts in them. One rig has a card that won't overclock for some odd reason, but... They are set at:

Top Left: 3x 950/170 1.100 V + 1x 850/1200 1.163 V = 1684 mh/s / 770 watts = 2.187
Top Rights: 4x 950/170 1.100 V = 1732 mh/s / 766 watts = 2.261

Both rigs were pulling between 766-770 watts as measured through my kill-a-watt. I changed the voltage on the 7 cards that will allow changes to 1.100 V, but noticed zero power consumption change through the kill-a-watt. I guess I am going to go shoot for what I can get on 1.06v tomorrow when I have to change some cards around.

[DeathAndTaxes]

It shouldn't take more than 10-15min to throw luck out of the equation as far as shares are concerned right? Does anyone else notice the same thing?

Depends on how of a difference.  If it is 50% higher then yes 10 minutes is more than enough.  However if it is more like 3% higher it could just be variance after 10 minutes.  You really want 3-4 hours to reduce variance enough to make small changes comparable.

this is going by the share/minute average in cgminer, maybe this isnt even accurate who knows?
[/quote]

[johnyj]

VRM are only capable of certain discrete voltage values.

So if 0.959v isn't a valid voltage the card will actually be running at voltage > 0.959V whatever the next higher step is.  Which according to johnyj (not verified by me) is 1.06V

So 0.959V, 0.96V 1.0V, 1.0123456789V it doesn't matter the card is running at the next higher valid step which may be 1.06V.

The only way to verify for sure is to pick a static clock (lower is better) and connect rig to watt meter (like kill-a-watt).  Change voltage and look for a change in wattage.  No change in wattage = no actual change in voltage.  Since wattage is going to have some variance anyways it may require measuring power instead (kWh) and time to get average wattage.

So something like

Set clocks to a static 700 Mhz.
Set voltage to stock.
Measure power for ~10 minutes. 
Divide power by exact time to get avg wattage.
Lower voltage and try again.

You will notice something like this

Voltage: 1.05V, 1.04V, 1.03V, 1.02V 1.01V = same wattage.  Then at some point the wattage will drop.  THAT IS THE DISCRETE STEP.

That's exactly what I did, I measured the change with only one 5870 installed, the result is directly visible on the power meter after each voltage change, I do not remember the exact voltage step location, but my card can run at 1.06v as high as 880Mhz, so I'm quite satisfied at this setting for now

[rograz]

Not sure why you guys are dicking around with trying to determine voltage by watching the power draw. Whip out a multimeter and dispel all uncertainty.

reflashing a card and checking for change in total power draw takes me 5 min tops, if I would want to check each type of card with a multimeter it would mean id have to take apart my rigs completely, it's not very accessible when you run 6 cards tightly packed with extenders in ghetto custom builds, duct tape/pieces of wire/cables ties ye you get the picture 

[johnyj]

I made some measurement again using my best 5870 card, here is the result:

0.000-0.950 stage 1, highest stable 730Mhz 320Mh/s consume 95W/card  -------------- 3.37 Mhs/W
0.955-1.060 stage 2, highest stable 880Mhz 395Mh/s consume 135W/card --------------- 2.93 Mhs/W
1.065-1.165 stage 3, highest stable 900Mhz (BIOS limit) 405Mh/s consume 171W/card ---------------2.37Mhs/W

So the highest voltage setting is definitely to be avoided, but weather or not to use the lowest voltage setting is up to each person's preference. As long as the heat and noise is not a problem, I'm satisfied with stage 2 voltage settings, anyway I do not want my hash rate drop too much, time is also a cost that should be put into consideration

BTW, I saw some screen artifacts when I run lowest voltage settings, stability could be an issue

[Littleshop]

I made some measurement again using my best 5870 card, here is the result:

0.000-0.950 stage 1, highest stable 730Mhz 320Mh/s consume 95W/card  -------------- 3.37 Mhs/W
0.955-1.060 stage 2, highest stable 880Mhz 395Mh/s consume 135W/card --------------- 2.93 Mhs/W
1.065-1.165 stage 3, highest stable 900Mhz (BIOS limit) 405Mh/s consume 171W/card ---------------2.37Mhs/W

So the highest voltage setting is definitely to be avoided, but weather or not to use the lowest voltage setting is up to each person's preference. As long as the heat and noise is not a problem, I'm satisfied with stage 2 voltage settings, anyway I do not want my hash rate drop too much, time is also a cost that should be put into consideration

BTW, I saw some screen artifacts when I run lowest voltage settings, stability could be an issue

I am getting artifacts on some of mine too at .95 but they still mine, no errors.  It has been over a week.

[rograz]

Fixed the artifacts on the only card that was doing it for me by using a bios from another card. The card with artifacts was a release day xfx 5870 that I used in my gaming rig before it was demoted to mining, other bios came from a ref xfx BE that was manufactured at least 4 months after release. Might just have been a fluke but who knows!

I also remember that 5xxx had a lot of problems with GSoD (grey screen of death) when idle at release (I was one of the victims :/) and that was fixed with later drivers. Think what they did to fix it was to disable the lowest idle clocks the card had, iirc they also released updated bios versions that supposedly fixed it later on so it might be some low voltage bug that is the culprit in all of this. Or it might just have been a fluke like I said :p I like rambling about random things!

[conspirosphere.tk]

After some tests, my favorite compromise is:
5870: 870-300@1.06v = 380-390 Mhs
5830: 830-250@1.05v = 266-267 Mhs
Less is too low for me at the moment.

[JWU42]

With Summer coming to those up North was reviewing this.  Interesting on the 3 ranges...

Gomeler ever use the MM to test?

[Gomeler]

With Summer coming to those up North was reviewing this.  Interesting on the 3 ranges...

Gomeler ever use the MM to test?

Not yet. I have a reference 5870 that I will be installing into a new rig once I receive a heatsink. Making a note to probe the card voltages while I'm testing the card out.

[JWU42]

With Summer coming to those up North was reviewing this.  Interesting on the 3 ranges...

Gomeler ever use the MM to test?

Not yet. I have a reference 5870 that I will be installing into a new rig once I receive a heatsink. Making a note to probe the card voltages while I'm testing the card out.

Thanks G!

[zvs]

After some tests, my favorite compromise is:
5870: 870-300@1.06v = 380-390 Mhs
5830: 830-250@1.05v = 266-267 Mhs
Less is too low for me at the moment.

I run my 5870's at ~215mem and use 128 worksize...  maybe 1.5mhash less..

[JWU42]

On a mixed 5970/5870 rig have increased efficiency from 2.6 to 2.9

5970's @ 675/180 @ .95 = 310 Mh/s
5870's @ 860/180 @ 1.06 = 390 Mh/s

Tried 870 on the 5870 and one got "SICK".  So trying it now at 860...

2.425 Gh/s at 840W = 2.88 Mh/J

[oldDirty]

Interessting, today i set the voltage from my 5850 from 1.044>1.012. Original was 1.088V.  
Still works now for ~8hrs with 850Mhz, same clockspeed like before. GPU Temps stay the same but Roomtemp rising to 23°C, +2°C.

[Dargo]

Great info in this thread. I can get 310 Mh/s (760/300) on my Sapphire 5850s at 0.95v using BAMT (Phoenix2). I wish I could go to a lower voltage, but there doesn't seem to be a way to do it. Are any of you doing something special to get below 0.95? I can tell my cards to go lower, but they don't do it, and in Atitweak 0.95 is listed as the lowest setting.