Maximising MH/J

[teukon]

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.

[Meatball]

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.

[cicada]

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  

[Meatball]

- use a cheap single-core CPU (eg Sempron 140 @45W / Celeron 430 @35W)

+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.

[trentzb]

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?

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.

[teukon]

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.

[teukon]

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.

[trentzb]

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 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.

[trentzb]

Which motherboard?

[teukon]

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.

[trentzb]

If this is your board M4A88T-V EVO I assume you have tried disabling the onboard 4250 right?

[CanaryInTheMine]

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

[teukon]

If this is your board M4A88T-V EVO I assume you have tried disabling the onboard 4250 right?

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

[teukon]

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

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.

[trentzb]

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.

[TiagoTiago]

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)

[bcforum]

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

[Meatball]

Switch your power supply from 120V to 240V. Most power supplies are ~2% more efficient at the higher voltage.

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?

[steelhouse]

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.

[teukon]

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.

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.