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MAGAT
Limp Gawd
- Joined
- Mar 2, 2012
- Messages
- 470
if you are like me and accidentally bought a 7970 with locked voltage for mining, you probably have a palm print on your face.
fortunately, the geniuses over at bitcointalk figured out how to edit your 7970 or 7950 bios with a hex editor to make it possible for undervolting.
this only works if you are interested in undervolting on a card with a locked voltage. i did it on my XFX 797A-TDKC and it worked perfectly.
just thought i would share it with you guys.
here is the link https://bitcointalk.org/index.php?topic=310434.0 and here's what it says in case you too lazy to click on the link.
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) <bh:00><bh:65><bh:04><bh:00> with your desired voltage in the same pattern, eg: to undervolt to 0.962V, 0962 = 0x3C2 = c2 03, so you'd replace with <bh:00><bh:c2><bh:03><bh:00>,
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
Frhed can be found at http://portableapps.com/apps/development/frhed_portable
fortunately, the geniuses over at bitcointalk figured out how to edit your 7970 or 7950 bios with a hex editor to make it possible for undervolting.
this only works if you are interested in undervolting on a card with a locked voltage. i did it on my XFX 797A-TDKC and it worked perfectly.
just thought i would share it with you guys.
here is the link https://bitcointalk.org/index.php?topic=310434.0 and here's what it says in case you too lazy to click on the link.
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) <bh:00><bh:65><bh:04><bh:00> with your desired voltage in the same pattern, eg: to undervolt to 0.962V, 0962 = 0x3C2 = c2 03, so you'd replace with <bh:00><bh:c2><bh:03><bh:00>,
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
Frhed can be found at http://portableapps.com/apps/development/frhed_portable