Topic: How to Hack Your Radeon 79x0 GPU BIOS (any version) to Undervolt it (Read 16384 times)

Cheers, Spoetnik. 

Yeah, the point wasn't to brag.  It was to state that I had experience and a "resume" to back it up.  All I did was try to educate how to *actually* change the I2C values for the voltage.

Also, it was world news.  Ask nVidia's PR department. 
http://www.brightsideofnews.com/news/2009/9/24/nvidia-sli-cracked---works-on-all-motherboards-now-.aspx

National vs world news doesn't change anything though.  The code still works the same way.

If you can't swallow your pride and admit ignorance, you're going to have a tough time learning.

I took the risk and flash the card with a 1084v bios, the original was 1250v.
The temperature only came down by 5º. It was at 84º and now it is at 79º.
Atiwinflash backed up a 256 kb rom, this one do not work. Use the  gpu-z backup that is 128kb.
The undervolt worked fine, but apparently this card is really hot either way.

EDIT: Still testing, at 1000mv, temperature is at 78º but fan velocity went down from 4000 to 3600 rpm. I read that at low voltage the 7950 cards went down to 65 or 70º. But this XFX must be really bad quality because it is still really hot.

EDIT2: I flashed a 975mv bios and when I opened cgminer, it never started mining.
Then I bricked the card, fixed it using an Nvidia as primary, and went back to 1000mv.
I had never flashed an ati card before. It seems ati cards are really good when it comes to flashing bios, you can fix a bricked card really easy.

TIP: If you use atiwinflash and it says bios upload failed, NEVER reboot the pc. Just wait a minutes and try again until the bios uploads succesfully.

@mar69theone
What did you do to unlock the voltage?
which was the default voltage and what did you change it for??
Did you have to change more data to get the correct checksum???
I have a locked XFX 7950 and want to undervolt it, but I am afraid to do it becouse this card doesn't have the backup switch...

Thanks!!

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
• 1 x 7970 @ 700kh/sec @ 350 watts

After undervolting modded stock BIOS

• 4 x 7950s @ 665 kh/s @ 900 watts @ 1.0v
  
• 1 x 7970 @ 730 kh/s @ 250 watts @ 0.962v

To modify your BIOS, follow the instructions listed below.  See Disclaimer below.

• Grab atiflash and save your bios ("./atiflash -s 0 bios0.back.up.rom" to save bios from card zero),
  
• Check that it produces a file of size 128Kb ("ls -lkh bios0.back.up.rom"),
  
• If it produced file of size 256Kb, these will appear valid but attempting to write them back to the card will always fail, leaving you without a valid backup! In this case, retry to read the video card bios again specifying an additional size parameter ("./atiflash -s 0 bios0.back.up.rom 20000"),
  
• You should save the bios from each card, then use diff to see which match and modify that subset, then flash all the cards,
  
• Please check all GPUs stock voltage in cgminer GPU Management and Bios Config File in output of "./atiflash -ai", these can vary between bios in "identical" brand GPUs,
  
• Transfer all bios to a Windows PC/laptop using WinSCP, or via Webmail if you do not have WinSCP
  
• Open the saved bios in a hex editor, we use Frhed,
  
• Convert that bios stock GPU voltage into hex, eg google "1125 in hex" if bios stock voltage is 1.125. The hex equivalent in this case is 0x465,
  
• Reverse the stock hex voltage, eg: 0x465 = 04 65 = 65 04,
  
• Using your hex editor, search and replace for (reversed stock voltage) with your desired voltage in the same pattern, eg: to undervolt to 0.962V, 0962 = 0x3C2 = c2 03, so you'd replace with ,
  
• Save the modified bios to a different file name so you can always write the original back if required,
  
• Unlock the bios for the card you wish to flash (eg: ./atiflash -unlockrom 0),
  
• Transfer the modified bios back to your (Linux) coin mining rig and write the modified bios back to the video card using atiflash with the -f parameter to bypass checksum checks. In our experience this can fail multiple times before succeeding and some bios require using different write flags (-atmel, -sst).
  
• Cold Reboot and use cgminer GPU Management to see new undervoltage in action!
  
• We recommend doing one card to start with and not the primary video card until you are confident with the process :-)
  

After doing all this above, you will save money and be able to run a cooler rig.  I now use 1250 watts total and it a beautiful space heater for my whole house

Happy Bios Flashing, Video Card Undervolting & Coin Mining!



If you Found this article useful, please send a donation to:

BTC: 1PoN7e4q5DMoTXiU2HYecbaGrb78mSxo6W
LTC: LNYFzi4ed8gBwk8joVpntk5apUcvndu2g9
BTB: BBe9NyL2uzne4ZEXax39huFzUH1XMD4a7t
BTG: gbpuqkpmZVhcJgZBQtmGRamSvLdEhQFEkM

DISCLAIMER: Any and all modifications done here is at your own risk.  I am not responsible if your hardware goes dead, gets damaged, or burns up.  This information is strictly for educational purpose.  Use at your own risk.

You want me to overclock instead of undervolt?  Now you're really confusing.  I'll never hit 1060-1100 mhz on those chips with my lowered voltage, and I intended it to be that way.

My voltage/clocks -- 3.27MH/J
Your clocks -- 2.955MH/J

Once again, you have no idea what you're editing.  I've tried to help, but you're still so sure of yourself (even though you've obviously not disassembled the code to that BIOS).  I've made national news for things I've done with video cards, but I'm sure you're still right.   

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

Good one

Have you by chance experimented with this utility?
http://www.techpowerup.com/forums/showthread.php?t=183423

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?:

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.)