How to Hack Your Radeon 79x0 GPU BIOS (any version) to Undervolt it

[cowandtea]

Guys, I have done this on Sapphire 7970 and Gigabyte 7950s.  I had undervolted the ROMs to have them running at lover voltages.
Before specs:

• 4 x 7950s @ 550kh/sec @ 1000 watts

After undervolting modded stock BIOS

• 4 x 7950s @ 665 kh/s @ 900 watts @ 1.0v
  

The idea of undervolting is pretty useful but 2 moments:

1. amm, you didn't state frequencies used before and after - really, only changing voltages affected hash rate?! ("I don't believe you!")

2. There are memory timings - and it does help if you can edit them. But I don't know how to do that.

E.g. 7850 from sapphire and 7850 from gigabyte can reach 375-400kh and up to 350kh "whatever you do" respectively; all with the same settings(like 1100/1250). HIS 7950 ICEQ does 585kh/s at 970/1000 and nothing more - whatever I try; raising mem speed to 1250 or whatever upper - doesn't do any good.

1: Both at Intensity 20, Thread Concurrency @ 40960, Shaders @ 1792, lookup gap @ 2, Threads @ 1, powertune @ 0
    Before undervolting, running 1090MHz CPU, 1500 MHz Memory
    After undervolting, running 1080MHz CPU, 1250 MHz Memory.  250MHz lower on memory speed yet gained 115kh/s

2: Nor do I but it does not affect mem timing if you are using the memory stock speed of your vid card.

Gigabyte and Sapphires work great for getting good high hash rates.  I had an XFX, was crap returned it.
Consider maxing out the Thread Concurrency as much as possible along with the shaders.  It worked for me and getting great speeds.  Scrypt is memory intensive so more memory it gets the more it can hash.

That is weird, undervolting normally only result in equal hash rate or lower. Maybe its due to powertune @ 0. hm...

[Samir_H]

@swiftshoot thanks for post and what are temperatures before and after?

[kuusj98]

Funny thing is, is that my HD7850's don't really use more power when overvolted, or use less when undervolted.
But, 100W is a huge win, such things mean ROI or no ROI.

Thanks for the guide, I thing many people will find this usefull.

Think most of 7850's are voltage locked. I have voltage slider on my asus/xfx cards and i can move it around. But if i check in gpu-z it's at the same stock value no matter what i do.

Both my Asus Hd7850 DCII have unlocked voltage, I can go down to 0.01 if I want to, but probably not too healthy for my card hehe...

[carly200]

can anybody verify those results?
I still wonder how the hashrate would go up through undervolting....

[sveetsnelda]

can anybody verify those results?
I still wonder how the hashrate would go up through undervolting....

Read my post in this thread.  This does not alter the voltage.  There is a utility that will allow you to change it though.

[carly200]

i read your post, still both don't make sense.

so what is it, that is stated in the first post?

[swiftshoot]

@swiftshoot thanks for post and what are temperatures before and after?

Before I was at 79-85c depending on the board...
After I was as low as 62-65c but now I tuned it to 72-74c so that I can heat my house... we getting cold nights here so having the GPUs heat helps us save on the Heating bills.

Funny thing is, is that my HD7850's don't really use more power when overvolted, or use less when undervolted.
But, 100W is a huge win, such things mean ROI or no ROI.

Thanks for the guide, I thing many people will find this usefull.

Think most of 7850's are voltage locked. I have voltage slider on my asus/xfx cards and i can move it around. But if i check in gpu-z it's at the same stock value no matter what i do.

Both my Asus Hd7850 DCII have unlocked voltage, I can go down to 0.01 if I want to, but probably not too healthy for my card hehe...

Undervolting will not damage your card... Overvolting it will.

can anybody verify those results?
I still wonder how the hashrate would go up through undervolting....

I would think it is all a matter of timing between memory and gpus... since they are not overclocked to push more and produce lots of heat they work in unison.  I was shocked too when I saw the results.  If I tried to overclock while undervolted, it would then drop in performance.  I think the bell curve gets shifted downwards as you undervolt.

[sveetsnelda]

I would think it is all a matter of timing between memory and gpus... since they are not overclocked to push more and produce lots of heat they work in unison.  I was shocked too when I saw the results.  If I tried to overclock while undervolted, it would then drop in performance.  I think the bell curve gets shifted downwards as you undervolt.

Go measure your card's voltage with a meter before and after what you're changing in the BIOS.  It isn't budging, I assure you.  Your power consumption changes are either differences in settings, or you're measuring when cards are hot vs cold.

[swiftshoot]

1: Both at Intensity 20, Thread Concurrency @ 40960, Shaders @ 1792, lookup gap @ 2, Threads @ 1, powertune @ 0
    Before undervolting, running 1090MHz CPU, 1500 MHz Memory
    After undervolting, running 1080MHz CPU, 1250 MHz Memory.  250MHz lower on memory speed yet gained 115kh/s

2: Nor do I but it does not affect mem timing if you are using the memory stock speed of your vid card.

Gigabyte and Sapphires work great for getting good high hash rates.  I had an XFX, was crap returned it.
Consider maxing out the Thread Concurrency as much as possible along with the shaders.  It worked for me and getting great speeds.  Scrypt is memory intensive so more memory it gets the more it can hash.

That is weird, undervolting normally only result in equal hash rate or lower. Maybe its due to powertune @ 0. hm...

here is my cgminer.conf

{
"intensity" : "20",
"vectors" : "1",
"worksize" : "256",
"kernel" : "scrypt",
"lookup-gap" : "2",
"thread-concurrency" : "40960",
"shaders" : "1792,1792,2048,1792,1792",
"expiry" : "2",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1",
"gpu-engine" : "1100,1080,1100,1080,1060",
"gpu-memclock" : "1250,1250,1500,1250,1250",
"gpu-vddc" : "1.020,1.01,0.962,1.003,1.08",
"gpu-powertune" : "0",
"auto-fan" : true,
"temp-target" : "75",
"temp-overheat" : "79",
"temp-cutoff" : "83",
"log" : "5",
"failover-only" : true,
"no-pool-disable" : true,
"queue" : "2",
"scan-time" : "1",
"scrypt" : true,
"shares" : "0",
"kernel-path" : "/usr/local/bin"
}

And CGMiner results.
cgminer version 3.1.0 - Started: [2013-10-18 22:46:23]
--------------------------------------------------------------------------------
 (5s):3.350M (avg):3.329Mh/s | A:53296  R:5269  HW:0  U:9.5/m  WU:3099.7/m
 ST: 3  SS: 265  NB: 15036  LW: 649635  GF: 190  RF: 52
 Connected to stratum01.hashco.ws diff 237 with stratum as user swiftshoot.2
 Block: cdc821b513950ac7...  Diff:539K  Started: [20:29:55]  Best share: 10.2M
--------------------------------------------------------------------------------
 [P]ool management [G]PU management \[S\]ettings [D]isplay options [Q]uit
 GPU 0:  72.0C 3236RPM | 667.1K/663.4Kh/s | A:10578 R:1033 HW:0 U:1.88/m I:20
 GPU 1:  73.0C 2199RPM | 656.7K/651.2Kh/s | A:10458 R:1026 HW:0 U:1.86/m I:20
 GPU 2:  72.0C 2841RPM | 728.5K/723.1Kh/s | A:11713 R:1064 HW:0 U:2.08/m I:20
 GPU 3:  72.0C 1883RPM | 653.6K/651.4Kh/s | A:10451 R:1050 HW:0 U:1.86/m I:20
 GPU 4:  73.0C 4638RPM | 645.2K/640.2Kh/s | A:10096 R:1096 HW:0 U:1.80/m I:20
--------------------------------------------------------------------------------

GPU 0: 667.7 / 663.4 Kh/s | A:10578  R:1033  HW:0  U:1.88/m  I:20
72.0 C  F: 78% (3244 RPM)  E: 1100 MHz  M: 1250 Mhz  V: 1.019V  A: 99% P: 0%
Last initialised: [2013-10-18 22:46:23]
Intensity: 20
Thread 0: 668.4 Kh/s Enabled ALIVE

GPU 1: 655.0 / 651.2 Kh/s | A:10456  R:1026  HW:0  U:1.86/m  I:20
73.0 C  F: 52% (2199 RPM)  E: 1080 MHz  M: 1250 Mhz  V: 1.009V  A: 99% P: 0%
Last initialised: [2013-10-18 22:46:23]
Intensity: 20
Thread 1: 655.2 Kh/s Enabled ALIVE

GPU 2: 726.9 / 723.1 Kh/s | A:11712  R:1064  HW:0  U:2.08/m  I:20
72.0 C  F: 79% (2781 RPM)  E: 1100 MHz  M: 1500 Mhz  V: 0.962V  A: 99% P: 0%
Last initialised: [2013-10-18 22:46:23]
Intensity: 20
Thread 2: 726.1 Kh/s Enabled ALIVE

GPU 3: 654.8 / 651.4 Kh/s | A:10450  R:1050  HW:0  U:1.86/m  I:20
72.0 C  F: 45% (1881 RPM)  E: 1080 MHz  M: 1250 Mhz  V: 1.003V  A: 99% P: 0%
Last initialised: [2013-10-18 22:46:23]
Intensity: 20
Thread 3: 653.9 Kh/s Enabled ALIVE

GPU 4: 645.5 / 640.2 Kh/s | A:10095  R:1096  HW:0  U:1.80/m  I:20
73.0 C  F: 29% (2229 RPM)  E: 1060 MHz  M: 1250 Mhz  V: 1.080V  A: 99% P: 0%
Last initialised: [2013-10-18 22:46:23]
Intensity: 20
Thread 4: 645.1 Kh/s Enabled ALIVE

[E]nable [D]isable ntensity [R]estart GPU [C]hange settings
Or press any other key to continue

[swiftshoot]

I would think it is all a matter of timing between memory and gpus... since they are not overclocked to push more and produce lots of heat they work in unison.  I was shocked too when I saw the results.  If I tried to overclock while undervolted, it would then drop in performance.  I think the bell curve gets shifted downwards as you undervolt.

Go measure your card's voltage with a meter before and after what you're changing in the BIOS.  It isn't budging, I assure you.  Your power consumption changes are either differences in settings, or you're measuring when cards are hot vs cold.

I don't poke my GPUs with wiring... I can see if at the wall... 1250 watts @ 3.329gh/s vs 1480 @2.9 GH/s is all I need to convince me.
GPUs are not Car engines... running hot or cold makes nominal difference.

Here is my Before Undervolting settings.
"intensity" : "20",
"vectors" : "1",
"worksize" : "256",
"kernel" : "scrypt",
"lookup-gap" : "2",
"thread-concurrency" : "40960",
"shaders" : "1792,1792,2048,1792,1792",
"api-port" : "4028",
"api-listen" : true,
"expiry" : "10",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1",
"gpu-engine" : "900,900,1080,900,900",
"gpu-memclock" : "1250,1250,1680,1250,1250",
"gpu-vddc" : "1.030,1.125,1.175,1.125,1.125",
"gpu-powertune" : "0",
"auto-fan" : true,
"temp-target" : "70",
"temp-overheat" : "77",
"temp-cutoff" : "83",
"log" : "5",
"no-pool-disable" : true,
"queue" : "10",
"scan-time" : "1",
"scrypt" : true,
"shares" : "0",
"rotate" : "1440",
"kernel-path" : "/usr/local/bin"
}

[EfterlysT]

Anyone that have a successful undervolted 7950 bios file to share ?

It would be much appreciated !

[sveetsnelda]

GPUs are not Car engines... running hot or cold makes nominal difference.

You are quite wrong.  Power consumption rises as temperatures within the ASIC increase (leakage increases because resistance increases).  AMD's 28nm chips are extremely sensitive to this, and the power consumption climbs rapidly above about 73-74c.  Go put 4 7970s in a rig, measure it at 60-65c and then measure it at 80c.  You'll see 80-100 extra watts being drawn from the wall, even though the fans spun DOWN.  Water cool the chips and you'll notice a pretty significant decrease in power consumption under load.  Lastly, you'll notice that power consumption is *much* lower when you first start your mining software.  Go measure it again after 15 minutes and be amazed by how much more power is being drawn after the ASIC heated up.

Once again, the number you are altering doesn't change the power consumption on ANY 7000 series BIOS.  I don't mean to sound pompous here and I'm only trying to educate, but I know what that value does and you clearly do not.  If you had spent enough time reverse-engineering that value, you'd realize that it only changes the voltage reported by ADL (and it changes the voltage on cards prior to Southern Island chips since they had a function that translated the voltage value into the proper commands to send to the voltage regulator.  The 7000 series cards do not have this.)

[sveetsnelda]

Here's an example with a GTX 480 and GTX 580.  There may be one out there for a Southern Islands chip, but I haven't dug around.  From experience though, I know that the 28nm chips have very high leakage at higher temps, and you don't have to get them as hot as the previous generation before you start seeing leakage ramp up significantly.

[johncarpe64]

Here's an example with a GTX 480 and GTX 580.  There may be one out there for a Southern Islands chip, but I haven't dug around.  From experience though, I know that the 28nm chips have very high leakage at higher temps, and you don't have to get them as hot as the previous generation before you start seeing leakage ramp up significantly.

Do you have one with ATI? Not a fan of nvidia, sorry

[sveetsnelda]

Did you even read the post that you quoted?     I didn't make that chart, and no CPU/GPU is immune to the laws of thermodynamics -- regardless of brand.   

[swiftshoot]

Anyone that have a successful undervolted 7950 bios file to share ?

It would be much appreciated !

If you want me to undervolt your BIOS, send me a link to it via PM...  Donations welcome.

[swiftshoot]

GPUs are not Car engines... running hot or cold makes nominal difference.

You are quite wrong.  Power consumption rises as temperatures within the ASIC increase (leakage increases because resistance increases).  AMD's 28nm chips are extremely sensitive to this, and the power consumption climbs rapidly above about 73-74c.  Go put 4 7970s in a rig, measure it at 60-65c and then measure it at 80c.  You'll see 80-100 extra watts being drawn from the wall, even though the fans spun DOWN.  Water cool the chips and you'll notice a pretty significant decrease in power consumption under load.  Lastly, you'll notice that power consumption is *much* lower when you first start your mining software.  Go measure it again after 15 minutes and be amazed by how much more power is being drawn after the ASIC heated up.

Once again, the number you are altering doesn't change the power consumption on ANY 7000 series BIOS.  I don't mean to sound pompous here and I'm only trying to educate, but I know what that value does and you clearly do not.  If you had spent enough time reverse-engineering that value, you'd realize that it only changes the voltage reported by ADL (and it changes the voltage on cards prior to Southern Island chips since they had a function that translated the voltage value into the proper commands to send to the voltage regulator.  The 7000 series cards do not have this.)

Still drawing 1250 Watts and getting 3.329 Mh/sec.  I have been running overnight.  I will set the temp lower to see if that will reduce consumption.

[swordfish6975]

So you guys are doing what I posted here?

The warning is probably a bit stern on that page, these cards have a small dual bios switch, I have dumped the read only bios and flashed it across to user area before.

some premade ones for MODEL: AX7950 3GBD5-2DHV5E in that thread above

some tips to make the process easier.
gpu-z has a button to dump your bios in windows.
then hex edit.
then use aitflash to load it in to the card with -f (force bios flash)

[sveetsnelda]

You guys are delusional.  Here, let me prove my point.  Here's a 7950 that I modified to run on FIVE volts.  You understand that this card should be melting down, right?:

[sveetsnelda]

P.S.  This rig takes 673 watts (at the wall) to run because I *actually* undervolted it.