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My power meter finally arrived and so I finally have everything I need to try and maximise MH/J.

I've done some basic things like undervolting the CPU and GPUs slightly but would like to know more about maximising MH/J.  Just to be clear, this is not about maximising profit, and I would like to maintain a reasonable level of hashing speed (at least 75% of record hashing rates for the same cards).

Right now my miner (2 x Sapphire HD 5850 Xtreme) draws 307 Watts (at the wall) and manages 722 MH/s (so 2.35 MH/J).  Any ideas how I might improve this?

As usual, I will tip BTC for significant improvements.

You've probably already done it considering you're down at 307 watts, but make sure you don't have any extra peripherals.

Also, you can underclock your memory, which might help a bit with power and heat.  I've been able to run my cards with as low as 185 Mhz Memory clock.  Also found anything below 300 clock seemed to work better with a worksize of 128 instead of 256.

Without knowing more, assuming this is a dedicated miner, offhand suggestions are

- boot from USB or network, no internal drives
- maximize cooling to reduce speed or even remove fans
- use a cheap single-core CPU (eg Sempron 140 @45W / Celeron 430 @35W)

If your mobo has a good bios you can reduce memory clocks, possibly voltages on your system RAM as well (disclaimer: may break stuff, ymmv, /notmyfault).  The only thing that needs to perform well to hash are the GPUs, spin everything else down as long as it's stable.

None of this will garner big results, but every little bit adds up over time.

/goes off to implement his own suggestions  ;D

+1 on the Sempron, -1 on the Celeron 430.  I have two rigs, each with one of those CPU's and the Celeron really just runs like hell whenever I try to do anything on it.  I know it's 10W, but if you plan on doing anything on that box and having it be responsive, it might be worth the Sempron over the Celeron.

If this is for the entire system then I think you have won. I don't know how you could scrape anything more out of it other than the tips the other folks have suggested. 2.35 Mh/s/W is impressive. I am right around 2.20 with ~1400 Mh/s.

Thanks for the help.

I've tried disabling the onboard devices but none of it makes even 1 watts difference for me so I left them all at default.  My system pulls 114 watts from the wall when I stop phoenix and am wondering if this 'idle' power consumption is excessive or not.

I do have an AMD Semperon 140 and it's underclocked and undervolted, I've also undervolted the RAM.

I have also worked very hard to maximise cooling and, at minimum fans, my cards are at 60*C and 46*C (added bonus, the miner is very quiet).

The two things I've not tried are doing away with internal drives (I'm currently using a 160GB Western Digital drive and this is being used constantly since I am also running bitcoind with my .bitcoin folder on the drive).  I will investigate parking this drive.

The other thing mentioned here I haven't tried is reducing the RAM speed on the cores significantly below 300 MHz and changing the worksize to 128.  I'll give this a go as it's easy to test.

Putting the bitcoin activity that I needed on a ramdisk and parking the drive reduces my power consumption by 7 watts (now down to 300).  It's a little inconvenient and configuring the system to boot from a usb or from the network doesn't seem to be too much hassle for 7 watts but it is a significant improvement that I didn't think of.

Could you give me a BTC address to donate to cicada?

Reducing the RAM clock and worksize lost me far too much hash rate to be viable.

I would think this is about right. When I measured our Sempron 140 rigs I measured with no GPUs physically installed and I did a sha1sum /dev/zero on the machine to bury the CPU. I measured ~65W at the wall for the system. So having 2 GPUs even idle is expected to draw something more and ~50W could be right in there.

I think maximum consumption on a typical 3.5" drive is ~12W or so last I looked.

Edit: Just noticed you already tried this.
I don't know that it will help much but try turning off any other peripherals via BIOS (audio, parallel, serial, etc). I don't know that it would actually power them down or help at all but it may be worth a try.

Underclocking the CPU/RAM may help a bit but I don't know if it would be worth it. When I measured the above Sempron systems at idle the system drew ~45W and increased ~20W when loading the CPU. I doubt your CPU is pegged running miners/bitcoind.

Hope this helps.

Which motherboard?

I only dropped 7 watts when I parked my drive, perhaps I should try removing it altogether but this would take quite a bit of setting up so I'll leave it.

I tried underclocking the CPU and undervolting the CPU and RAM in the bios and found I instantly dropped 9 watts.  It's possible that when editing the BIOS that the chip and ram are in some kind of high performance mode and that the running miner would behave quite differently but it's caused no harm so I've left it.  The system is now quite a lot slower but, you're right, phoenix and bitcoind together only want 6% of the CPU at all times (used to be much less).

The motherboard is an M4A88T-V EVO.

If this is your board M4A88T-V EVO (http://www.newegg.com/Product/Product.aspx?Item=N82E16813131668) I assume you have tried disabling the onboard 4250 right?

You could make sure that no lights are working... :)

Yes, the onboard graphics are disabled.  Thanks for pointing that out though.

But I need my lights.  The power LED is particularly important.  I don't see how it's possible to tell whether or not the miner is switched on without the power LED.

If you want to get silly...

If you have clocked down the CPU in BIOS you could probably get away with disconnecting CPU fan and running passive. Also you might be able to shave a W or two if you drop your RAM to 1GB unless you are already at 1GB (pull a stick or more).

Hmm, disconnecting USB keyboard/mouse when not using them might save a W if your lucky.

Turn off RAID features in BIOS and any related BIOS/ROMs.

I can't think of anything more at the moment. Report back your final results.

Since you need network for mining you could ping the machine to see if it's running (not sure if the additional wattage used by the machine you're pinging from from time to time will average out more than what is consumed by the LEDs though)

Make sure your power supply is properly sized, peak efficiency is about 50% load. You probably should be running a 600W supply with an 80+ gold rating. It's tough to pick the proper supply without plugging it in and measuring it.

Switch your power supply from 120V to 240V. Most power supplies are ~2% more efficient at the higher voltage. If memory serves, power companies charge based on whichever phase is drawing the most power. If you have two lightbulbs connected to the same phase you will pay twice what you would pay if the lightbulbs were on separate phases. I can't find a reference for this though. I did find a page discounting this. I guess I'll have to run the experiment.

Make sure you are plugged in as close as possible to the breaker panel to avoid losses in your wiring. My project for the weekend is to drop a new 240V outlet into my basement (so I don't pop a breaker when I run the microwave.) Power strips, though useful, are energy wasters also.

http://www.anandtech.com/show/2624/3 (http://www.anandtech.com/show/2624/3)

Hmm, can you elaborate on this?  Is this something you can do without having a special 240V outlet put in or can it be run over your normal lines?

That is amazing what voltage is a good voltage to keep cards at to optimize energy.  Saw in an older post you were running at 1.01v/900/300 with 735 mH/s.

I'm already at a single stick of 1GB ram.  I've tried toggling various elements in the bios but there was no apparent change in the power draw so I left them all enabled; I'm not using sata, usb, firewire, or on-board sound, but they are all enabled in the BIOS.  I'll try taking all of these off next time I go through a power cycle and see if it makes a difference when actually running the miner properly.

Lol ;)

My power supply situation is not optimal for minimising power consumption.

I'm using a Scythe Chouriki 2 850W power supply (80+ silver certified) and it claims to be about 89% efficient at a load of 300W, see http://www.techpowerup.com/reviews/Scythe/SPCR2-850P/5.html (http://www.techpowerup.com/reviews/Scythe/SPCR2-850P/5.html).  I was originally using a 650W OCZ supply of some kind but it was quite a bit louder than any other part of my system.

For the purposes of this, the psu is plugged directly into the wall.  In reality it is plugged into a 4-gang which is plugged into a 10 meter long 2-gang but I've put the power meter into the 4-gang and am only interested in the power draw at this point.  When I move I'll probably manage to arrange to have it plugged into the wall directly.

The voltage 'at the wall' is 243.6V.

I'm still not very sure about minimising voltage but if you are trying to maximise MH/J then I'm almost certain that you need the card voltages below 1V for 5850s.  Of course, you may be willing to pay more than the cost of power for your Bitcoins and so it may make sense to increase the voltage.

When I posted before I was not aware that the VRMs on the 5850s handle voltage in multiples of 0.0125V (I'm not certain of this but fairly confident).  Thus, I was really running at 1.0125V/900/300.

My cards are currently running at 0.9875V/850/300 (352.7 MH/s +/- 0.1) and 0.9875/895/300 (371.6 MH/s +/- 0.2) for a total of (724.3 +/- 0.2).  My power consumption at the wall with the cards running is 304W +/- 2W.  When I close the mining software the cards fall back to 157MHz@0.95V and the power consumption drops to 111W +/- 1W.  I'm still running from my hard-drive and preventing it from going into any kind of power saving mode with bitcoind so there is a saving I'm not applying here too.

I've not had time to verify the stability of this setup but the cards did run all night at 850 and 890 respectively.  895 is a new venture.

Running a card at 0.9875V at 850 MHz yields similar MH/J as running it at 1.0125V at 900 MHz (taking system load into account, if you just count the cards then going up to 1.0125V and clocking up to 900 MHz actually lowers my MH/J).

Honestly, finding the correct voltage and clock rate for the best stable MH/J requires testing as every card is different.  I'll point out that my cards both seem to be pretty good at overclocking so you may find it difficult to even get above 800 MHz at 1V.  I'm using Linux, the cards are configured to give no signal, and I'm using Zalman ZF3000A coolers, and the ambiant temperature where I am is currently peaking at 21*C so I have some natural advantages when it comes to stability too.  My good card clocks to 1025 MHz stably at stock voltage and went for 3 hours at 1110 MHz at 1.25V (461.1 Mh/s) so it's not bad even compared to 5870s!  I'm using everything I learnt in competing for high hash rates to maximise my efficiency at low voltages.  PM me if you'd like more details.

Very informative thread -- thanks.

making sure the PSU is drawing fresh (ie not heated from the cards) air may help the PSU efficiency. Im unsure but I do know the hotter they get the less power they can deliver. whether cooler = slightly better efficiency is true or not I dunno but even 1 or 2 % = 3-6 watts on your setup. 

and man, 300 watts that whole system on those two cards? sweet! I pull 300 watts from the wall on a P4 prescott/single 5830 rig. no DVD, other cards, one HD.  Ill have to try undervolting the 5830. cant mess with CPU/mem stuff as that rig is a HP/Compaq business computer work gave me when they retired it. no BIOS options for the good stuff. that thing sat for ages in the basement, never thought Id would actually use it lol.

I stopped my cards and the power went down to 98 watts with the stock fans still on.  I did the test earlier in year before turning cards on and the base power was 78-86 watts.  However, the cpu-z ghz won't show 3.3 ghz but something less.

stock bios, stock settings
2500K intel sandy bridge, stock clockings
Gigabyte Z68MA-D2H-B3
2 dummy plugs and using intel graphics
8 gb ram (2 sticks of 4)
no hd, SSD
thermaltake 750W 80 plus bronze

6870 1.075/900/300 277 mh/s
6950 1.075/870/300 357 mh/s

total 376 watts  = 1.68 Mh/J

My PSU is certainly getting fresh air (not a problem with a rig mounted on a board).

I just discovered that increasing all the fans to maximum increases the load by 7W total right away but if I leave the system running for 15 minutes then the power consumption slowly drops until eventually I'm actually saving 6W (so down to 298W total)!  It seems the temperature of the gpus has a pretty serious effect on power consumption.  Unfortunately I cannot make much use of this because the miner is too loud to run like this 24-7.  It's a shame, 2.43 MH/J would have been awesome.

Undervolting my cards and maxing the fans really did a number on my temps: 44*C and 36*C respectively (the 44*C is sucking in warm air from the other card).  At 36*C and churning out 371.6 MH/s you might guess my 5850 was under water :D.

You are getting much lower base-system power consumption than I am (I'm at 111W with both cards idle).  I'm sure the HDD is one culprit but it's not enough on it's own to explain this gap.  I'm also only running 1GB of RAM.  I can't even pretent to compete with this, well played.  My high MH/J is probably partly due to the efficiency of the 5850s and partly because my cards are running at a much lower voltage (0.9875V).

It must be intel.  There are even lower watt intels out there.  I will try to go 1 volt, but with prices a $13, any mh/s at about 0.3 Mh/J is making money.

Could be.  My main computer consists of an intel chip and board and consumes about 55W total at 100% system load.  I'd expect to lose about 70-80 MH/s by taking both cards from 1.075V to 1V so and for your Mh/J to increase significantly but if you are profitable at 0.3 Mh/J then surely the 70-80 MH/s is worth quite a lot more than the power you will save.

My personal motivation for undervolting is to decrease noise levels and I know I would be more profitable at stock voltage.

You are doing well to be profitable at 0.3 Mh/J.  I'd be at a loss below 0.5 MH/J, but I guess that's just power costs.  Ah well, I can't have all the advantages I guess.

I kept getting crashes looking for sweet spot, but

1000/800/400 both, too many crashes so I stopped here

6950 2.59 mh/J 328 mh/s
6870 2.85 mh/J 246 mh/s

311 watts wall  1.84 mh/J
98 watts base

How did you get these numbers? Did you measure cards individually?

Dual gpu cards are more efficient than having two single gpu cards.  Trading in your two 5850s for a single 5970 or 6990 will increase your mh/s and lower your energy use.

Mobile gpus are more efficient still.  My dream rig is a desktop mobo and power supply with 10 6990m gpus.  Obviously it is not cost efficient to build one (yet).

Nice.  How have you accounted for the proportion of the base wattage which is going to the cards in idle mode?

I found that the maximum overclock is pretty much a hard line at lower voltages.  My cards are at 850MHz and 895MHz.  If I clock either of them up by 5 MHz they crash instantly (tried twice with both).  They've been running at 850MHz and 895MHz with no problems for 36 hours now.  I experienced the same thing at 1.0125V on my slower card where 900MHz was very stable and 905MHz always crashed instantly.  I may have to start moving by 1 MHz intervals.

At higher voltages I get all sorts of nonsense.  Sometimes my good card will run fine at 1035MHz for 36 hours.  Sometimes it will crash when I try to run it at 1025MHz.  Sometimes I'll get kernel errors.  All at about 55*C!  I just don't understand it.

Note: My cards are very much dedicated to mining and I don't think any other program is trying to use the cards.  In particular, when I plug a monitor into a card I get no signal.  I've seen some people trying to run a GUI at the same time which can seriously affect stability.

teukon,

Wow, you've got me beat big-time. I'm hashing at a similar rate with two 5850s (not the extreme version), but pulling a little under 400 watts from the wall (measured with Kill A Watt). Since you aren't booting from usb, I assume you have tried disabling legacy usb support? I've read that this is a bit power hungry (but of course don't do this if you use a usb keyboard for accessing bios). Also, if you happen to be using a usb wireless card, I discovered by accident that switching to an ethernet connection to my modem dropped power consumption by about 5 watts (and the wireless card is still plugged in). Did you see the biggest drops from undervolting the CPU and GPUs? I have an Athlon II 250 Regor CPU and my PSU is about 5% less efficient than yours - that is probably around +40 watts right there. Still, given what you have achieved, I ought to be able to get down to around 350 from the wall while staying above 700 Mh/s, which would be good enough for me.

I have the base of 98 watts turn one card on write watts, turn card off and turn other card on write watts.  subtract 98 from them and (mh/s)/watts = mh/J.  so I don't measure individually and I am not 100% of my baseline because it was once 86 watts.  I am amazed the slight lower voltage really cuts the watts.  I know I can do better.

That would not be the total draw per card then. To find per card total consumption you would have to remove all cards, take measurement, insert a card, take idle measurement, run miner take final measurement. I saw ~20-~30 W per card at idle doing this which would drop your mh/j number down to where it sounds right. Your ~98W includes power consumed by GPUs at idle...right? They don't idle for free. :)

Reduce ram clock to about 1/3 your core clock, the 300mhz is a reference everyone throws out. I've done this on all my cards, it doesn't effect the performance. Even if you have to run it a bit higher, say 400mhz, that should be more than plenty and it's saving you 5-700mh/s of memory clock that isn't getting used.

The 6xxx series work better with 256 work size.

Haven't read through the entire posting yet, but have you tried underclocking/volting your hypertransport? Slowing down the pci/e lanes? I mean... if your card is using 16 lanes, and you only "need" one lane, then couldn't you reduce the lane to 1/16 the original speed and still maintain overall bandwidth?

Use services.msc in windows to disable stuff your pc does not need to be running. Could shave cpu cycles allowing you to slow your cpu down even further.

Edit: I get the idea you are not running windows. So scratch that last line.

I have no idea but I've been told that my chip is very efficient so that must help a lot.

I think the bulk of my power saving may come from running the cards at low voltages.  At stock voltages I was using quite a bit more than 400W but with a 0.1V undervolt (1.0875V -> 0.9875V) on both cards 304W is my average draw.  Unfortunately, I had to lower the clocks on the cores to get stability back; 975MHz -> 845MHz and 1020MHz -> 895MHz respectively.  I was running at 850 and 895 but my 850 card crashed after 36 hours.  What voltages are your cards at?

I haven't disabled USB in the BIOS despite the fact that I have no USB in use.  I have no SATA, sound, firewire in use either but I left them on in the BIOS because I didn't see a difference in the power draw between enabling them and disabling them (I only checked power consumption in the BIOS though).  All I changed in the BIOS was the CPU voltage, CPU and RAM clocks, and I set the motherboard to be always switched on.  Given all the people talking about tweaking the BIOS I think I'm going to have to go back and have a proper look at this.

I also keep thinking about the possibility of doing away with the hard-drive but there's a fair bit of work involved in unhooking this for what amounts to 83p (1.34 USD) per month.

I'm at 300MHz.  I meant that decreasing to 180MHz and dropping the worksize from 256 to 128 seems to do me no good no matter what my other settings are (Sapphire HD5850 Xtreme).


No, I originally tried to underclock/undervolt everything as sensibly as I could but ended up but couldn't boot at all and ended up having to reset the BIOS/CMOS/whatever.  Since then I've just touched the CPU and RAM setting and have been afraid to touch any of the dozens of other settings for breaking my board (I have no experience with this kind of thing).  If you can give me a little more detail about this I'll try it and see if it helps.


Yep.  You can safely assume that I'm not running any 'services' at all.  Got a daemon or two running but powertop thinks they're all benign.  Linux is much easier to configure with respect to power consumption than the BIOS because of all the helper tools and documentation so assume that the OS related stuff is largely done.

you need to reboot for BIOS changes to take effect. shut off legacy usb (if your not using it) coms, printer, sound, raid, all that. probably save only a couple watts if that though.

tried underclocking the PCIe bus? how about undervolting other chips (southbridge?). this last depends on your bios/chipset. Im not up on AMD stuff, so I may not have the right term.

I did save changes and reboot to read the new power drain but didn't go as far as booting the system in full and running the mining software (would have taken hours to test all of the different settings).  I did notice that the power savings were negligible so I didn't bother but I have to admit the 4W in my 304W read-out bugs me.

I'm not up on AMD or Intel stuff.  I've not touched PCIe buses, northbridge, southbridge, et cetera.  Do you think that more than a 1-2W saving could be made here?

I finally took the time to give the BIOS a good stripping.  I took out everything non-essential (USB, SATA, onboard graphics, firewire, sound, and various motherboard bits) and lowered the voltages and clocks of everything I could as far as they would go (a 0.3V undervolt for CPU, RAM, and NB).  I didn't touch the special DRAM pages as they really looked quite hard.  My CPU is now at 6% usage but I don't notice any sluggishness as one might expect.  The total power saving of this was 4W so I'm now down to 300W.

Unfortunately, my card at 850 MHz crashed this morning (it lasted for 36 hours or so) so I've had to pull the clock rate back to 845 MHz and this has cost me 2.1 MH/s.

My system is mining at 722.8 MH/s (+/- 0.2) and draws 300W (+/- 3W depending on temperature) giving me 2.41 MH/J.  I've decided that the HDD stays so this is probably as far as I'm going to go with this.

In summary it seems that the most important factors for determining MH/J are:

1) Low voltages on the cards.
2) Efficient PSU (just increasing mine just from 89% to 92% would save me 10W).

Thank you all, I've sent my tips to those whose comments have helped me.

If you want to keep your temps down without maxing out the gpu fans, you could try a case fan placed above the cards or at either end, experiment with pushing vs pulling air over the cards to see what gets you the best temps.  I have a bunch of case fans pushing air down onto some of my 4 gpu rigs and that's dropping them all by about 10 degress C.  In another room I have a desk fan blowing across a couple of caseless rigs.  That's achieving a similar 10 degree drop.   I don't know exactly how much juice it uses, about 15w IIRC.

teukon,

Thanks very much for this information. My cards are currently at stock voltage, so I will first try lowering the voltage and see where this gets me. I'm hopeful that I can add a third 5850 and not be pulling much more than I am now (say keeping it under 450w or so).

Um, you shouldn't be switching the PSU to a different voltage if your electric lines aren't actually running that voltage. Ie: if your breaker is 110/120v you can't just put the PSU on 208/240v to save energy. Further more, if your breaker is 240v and you put the PSU on 120v you'll fry the PSU immediately. Finally, most PSUs these days are "auto switching" which means it will adjust to whatever voltage you plug in - so there's no switching it manually anyway.

You're welcome.  450W for 3 cards looks perfectly possible.  Just be aware that your maximum stable clocks will reduce quite a lot. (I lost 130 MHz from both cores with a 0.1V undervolt).

Less than 450W is easy, but it depends on how much hashing rate you are willing to sacrifice. I have "silent mode" for a miner with 2x5850 and 1x5870 which uses 385W, but the hashing rate is only ~920 Mh/s. I only use it on really hot days or when I don't want fan noise, though.

What shotgun said.

If you are setting up a serious mining rig you will want/need more power than can be supplied via standard wall outlets and it doesn't cost any more money to have 240V outlets installed instead of 120V outlet. If you don't KNOW how to do this already, hire an electrician. Mucking about in your breaker panel without knowing what you are doing could kill you.

Don't forget that going larger may pay more than optimizing Mj.

I am setting up a mining data center now and the rent is paid fully and over by the savings per KWH from private rate to industrial power. That in including on site admins ;) Requires some Investment, though.

This is a very efficient setup.  Might I enquire as to what your voltages and clock rates are for this silent mode?  Noise is the most important factor for me.

Yes, it's good to remind people every so often on this thread that maximising Mh/J is not the same as maximising profit.  I've seen many people complain about this on the few threads which talk about maximising Mh for fixed hardware (or hardware+clock rate).

Good point. I was assuming my hash rate wouldn't take that much of a hit. I'll undervolt my current cards and see where I end up. Am I correct in inferring that you had over 400 Mh/s from your 5850 extremes at stock voltage? If so, you had some great cards to start with, and I'm not quite so lucky. My limit is about 350/375 for the two cards I have.

Yes, I was getting around 402 Mh/s (970 MHz) on one card and 423 Mh/s (1020 MHz) on the other completely stable.  Undervolting by 0.1V took me down to 351 Mh/s (845 MHz) and 372 Mh/s (895 MHz) respectively and I'm still testing for stability so they may drop a little more (currently they've been running like this for over 48 hours).  The bulk of this hashing power comes from high clock rates and although I believe I have lucky cards I'm fairly sure this also has something to do with removing the GUI.  If you are using Linux then feel free to PM me for details.

Because your clocks are lower to start with you will probably not lose as much hashrate as I did with a 0.1V undervolt.  Also, because your clocks are lower, your cards will be drawing less power anyway so you might manage around 1.0125V on all three cards at under 450W.  Just as with overvolting, undervolting will give you diminishing returns; as you drop the voltage in 0.0125V increments you'll find that you'll lose larger and larger chunks of hashing power and save smaller and smaller chunks of power.  To maximise MH/J you'd probably have to go lower than 0.9875V but to maximise profit you'd be better off with something near stock voltage.  If you can handle the heat then I'd recommend going with the highest voltage that your PSU can handle comfortably and efficiently (try to find a graph of the power efficiency of your PSU).  Depending on the efficiency of your base system I'm guessing 1V or 1.0125V.

What do you mean by this?

You can shut off alot of the window effects in Linux each of which take some GPU time to handle. Transparency is particularly nasty.

I meant that I configure my cards to not drive a display at the same time as mining.  If I plug a monitor into one of my cards I get "no-signal", rather than some console or GUI mode.  I drive and monitor the cards by ssh.  This is the logical conclusion to tricks such as 'disabling desktop effects' or 'disabling Flash hardware acceleration'.  The tricky bit is still being able to modify voltage and clocks (aticonfig is not very sophisticated, makes bad assumptions, and is closed source) but it's at least possible with my cards.  I'd go into more detail but it's very much off topic for this thread.  I have no idea how to do this in Windows I'm afraid.