SAVE money - undervolting 7970 XFX, self made VBE7 bios = TABLE OF CONTENTS =

[Amgclk65]

Ive got my 6 270's running 700 watts or so now as well. take a look

https://i.imgur.com/udVQvH8l.png

https://i.imgur.com/LAuiAqP.png

https://i.imgur.com/QdQhDMfs.jpg

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[virtualreality69]

Ive got my 6 270's running 700 watts or so now as well. take a look

Very nice on the 270's!  .955v is very good!

You must have some really good cards. Some of mine were unstable below and around 1.0, but they're all very stable at 1.100. I'll have to go another round of testing to see if I can get them stable at 1.0.

My biggest problem now is that they're running on Linux, which I haven't found a good under-volting guide for. So if I wanted to do some testing I'd have to pull them out of the rig I made and put them in a windows box to flash with ATIflash.

Great work!
- VR

[Wipeout2097]

Are those, Gigabyte 270's?

[Amgclk65]

Ive got my 6 270's running 700 watts or so now as well. take a look

Very nice on the 270's!  .955v is very good!

You must have some really good cards. Some of mine were unstable below and around 1.0, but they're all very stable at 1.100. I'll have to go another round of testing to see if I can get them stable at 1.0.

My biggest problem now is that they're running on Linux, which I haven't found a good under-volting guide for. So if I wanted to do some testing I'd have to pull them out of the rig I made and put them in a windows box to flash with ATIflash.

Great work!
- VR

Thanks.
what engine clock and memory speeds are you using at 1.0mv?

[Amgclk65]

Are those, Gigabyte 270's?

Yes, three of them are. Undervolted via hex edit.

[virtualreality69]

Amgclk65,
Thanks for updating the post!  You made me re-visit my 6 x 270 setup and realize that I was pushing WAY too hard for those final few Khash.  Running slightly lower hash rate (5-8%) and consuming significantly less power (20-30%) IS THE WAY TO GO.

I'm now running 900/1080 intensity18, powertun -18%, with an expectedly lower hashrate (380 kh/s avg), but surprisingly close work units per minute (350wu/m) to what you're getting.

The rig hasn't been running long enough for exact results, but I'll update in a day or two with additional figures. Initial power consumption has been around 690 Watts (linux usb flash drive build, no HDD, no optical drive, no case fans).

If testing at 1.000V @ 900/1080 goes well I'll push for under 1.0.  Last time testing 1.000 volts I suspect my core clock and memory clocks were too high causing instability. 

If anyone cares I'm running Asus D2C R9 270's.

Cheers,
- VR

Ive got my 6 270's running 700 watts or so now as well. take a look

[Amgclk65]

Thanks virtualreality69 !
Yeah at one point I was doing the same. Trying to squeeze every last hash I could out of my 270. I finally got smart and starting playing with a ltc calculator and realizing the it really wasn't netting much income/ltc coins for the extra 300-350 watts. What's really cool now is that I can keep mining ltc with the difficultly increase in the last week or so. I guess what's hard to grasp is that in the gpu mining game, is the hash/watts is a huge factor. Most small gpu mining people like me want the most hash rates we can get off your hardware.
Low clock speeds and under volting is where it is at.

[Number6]

Hey guys

I also been going through my GPU based rigs trying to eek out another month or so before shutting them down for good. I have started buying the gridseed based devices, but like many of you I still have a significant investment in GPU rigs and would like to keep them up running as long as possible/profitable to gain back as much ROI as I can.

I have a 5 X 270x box with XFX cards that I have flashed to use an even 1.000 voltage and I have been running them at 950/1225. This nets me about 400 khash per card for a total of 2 Mhash for the rig. The power draw at the wall is just about an even 600 watts (jumps around 595-605). The cards are also running much cooler (around 50 C) which will help with the coming summer heat. This setup also brings me back to the realm of earning roughly $2 for even $1 in electricity I consume.

For a bit of history, I had flashed this rig before to around 1.1 volts or so, but as others already mentioned, when pushing the cards to hit 450 khash each I could not go lower on the voltages and remain stable. Thanks for the suggestion to try running at lower clock speeds to get the lower voltage settings to run stable. I do not quite have 24 hours yet on my newly configured rig, but will report back once I am confident in its stability. I have 5 more rigs like this to go and as I said earlier I would like to keep them going as long as possible.

[virtualreality69]

Good to hear Number6!

Try playing with intensity as well. I've found that just because you increase the intensity (and get a few more kh/s) you dont necessarily get more accepted shares.  On my 6 x 270 rig I found that intensity 18 gets almost the same amount of work units per minute (and accepted shares) as intensity 19 (dispite running at 4% lower hash rate).  

Power savings on intensity 18 vs 19 is  minimal (but existent). Power savings on i18 vs i20 is enough to call "significant" (without doing the exact numbers).

Look into intensity vs power savings vs accepted shares.

Cheers,
- VR

[Number6]

Good to hear Number6!

Try playing with intensity as well. I've found that just because you increase the intensity (and get a few more kh/s) you dont necessarily get more accepted shares.  On my 6 x 270 rig I found that intensity 18 gets almost the same amount of work units per minute (and accepted shares) as intensity 19 (dispite running at 4% lower hash rate).  

Power savings on intensity 18 vs 19 is  minimal (but existent). Power savings on i18 vs i20 is enough to call "significant" (without doing the exact numbers).

Look into intensity vs power savings vs accepted shares.

Cheers,
- VR


quote author=Number6 link=topic=395004.msg6499171#msg6499171 date=1398979256]
Hey guys

I also been going through my GPU based rigs trying to eek out another month or so before shutting them down for good. I have started buying the gridseed based devices, but like many of you I still have a significant investment in GPU rigs and would like to keep them up running as long as possible/profitable to gain back as much ROI as I can.

I have a 5 X 270x box with XFX cards that I have flashed to use an even 1.000 voltage and I have been running them at 950/1225. This nets me about 400 khash per card for a total of 2 Mhash for the rig. The power draw at the wall is just about an even 600 watts (jumps around 595-605). The cards are also running much cooler (around 50 C) which will help with the coming summer heat. This setup also brings me back to the realm of earning roughly $2 for even $1 in electricity I consume.

For a bit of history, I had flashed this rig before to around 1.1 volts or so, but as others already mentioned, when pushing the cards to hit 450 khash each I could not go lower on the voltages and remain stable. Thanks for the suggestion to try running at lower clock speeds to get the lower voltage settings to run stable. I do not quite have 24 hours yet on my newly configured rig, but will report back once I am confident in its stability. I have 5 more rigs like this to go and as I said earlier I would like to keep them going as long as possible.

Yes, I have also been playing around with the Intensity setting too. I do have it at 18 right now, but as I mentioned I have only been doing this under 24 hours so no real data to compare with yet. I am flashing another rig at this moment, and will then have something similar to compare with.

What is the lowest voltage you been successful with? I am still running a bit higher clock rates than you have posted, but if I can shave another 100 watts off somehow I would be happy, even if it means going down to 1800 khash which at 500 watts would be sweet.

[virtualreality69]

1.000V is the lowest I've gone on my 270's, but that's due to their setup which discourages changes.  Its a Linux rig in a closet under the stairs with no monitor/keyboard/mouse access.  To test a new voltage I have to shut it down, pull it out, hook it up to the closest monitor, flash, make sure nothing was bricked, and then stick it back in the closet.  

I think Amgclk65 has his at 0.955 which would be a big power savings over my 1.000 (possibly up to another 100 watts).  That might get my rig down to the low 600 watt range.

I may test the 270's this weekend depending on how much time I have. My 280x's are all at 1.100v, I'd love to test them again soon too.  

UPDATE:
So far, from stock Ive gotten:
2 x XFX 280x's. 680 watts to 450w (with 4 case fans, 2 HDD, and CPU water cooling on my 8350) only dropping 125 kh/s from stock.
6 x Asus D2C 270's. Down from 875 to 690 (currently only at 1.000v)
3 x PowerColor 280x's. 900 watts to 700 (while only dropping 90kh/s)!! 5C to 8C temp drop for all cards. I love these cards!

- VR

Yes, I have also been playing around with the Intensity setting too. I do have it at 18 right now, but as I mentioned I have only been doing this under 24 hours so no real data to compare with yet. I am flashing another rig at this moment, and will then have something similar to compare with.

What is the lowest voltage you been successful with? I am still running a bit higher clock rates than you have posted, but if I can shave another 100 watts off somehow I would be happy, even if it means going down to 1800 khash which at 500 watts would be sweet.

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[Amgclk65]

virtualreality69..
I had the same problem as you. I hated flashing the bios on my headless rigs. Till I discovered ati_win_flash. It allows you to flash the cards within windows. So I just team view into my rigs and and play with different voltage and bios with VEB. There so easy to use guides online regarding it.

[virtualreality69]

Amgclk65,
All but the rig I use for gaming are running linux :/

UPDATE:
Dropped my PowerColor 280x's down to 1.075V and that system's now pulling 700 watts and pushing just over 2Mh/s.
Now the PowerColor's aren't too far from the 6 x 270's @ 1.000v = 2.25mh/s pulling 690watts!  Its a race to the best kh/watt!!!

UPDATE:
The 270's have been running @0.955V stable for a while now.  Full system load is down to just ~630 watts!!  I even managed to pull a few more kh/s with the lower voltage (900/1080 @i18).  

~540watts (for just the GPU's) = 4.256 kh/w!!. Wattage is down 30% while only loosing around 10% hashrate.  Theoretical profits are up over 30%!

[virtualreality69]

Ive got my 6 270's running 700 watts or so now as well. take a look

How about posting a picture of your 6x270 rig?  I'd love to see it!

Have you tested a voltage below 0.955? Mine have been rock solid there, and I'm interested in trying something lower. I'm going to test 1.038v on my XFX 280x's. 

Cheers,
- VR

[virtualreality69]

If anyone is interested, I'm upgrading from my undervolted 270's and they're for sale.  

Keep in mind these cards are pulling 35% LESS power (88watts vs 133 watts) than stock 270's, and getting well over 4.0 kh/watt.


I've created a full post on the marketplace forums:
https://bitcointalk.org/index.php?topic=645037.msg7400018#msg7400018

Feel free to bump or comment/question in that thread.

Cheers,
- VR

[virtualreality69]

Anyone else have good luck running a super low voltage on their cards?  I'm curious to hear what others have been able to run.