Aikei

You can look my guide http://forum.techinferno.com/clevo/4316-%5Bguide%5D-amd-hd7970m-enduro-vbios-modify-flashing-p1x0em-etc.html

it all depends on the quality of the videocard. My Card is unstable after 970Mhz Core clock without overvolting.

I can help you in this weekends, please wait.

It's easy, but for beginning try to flash any your vbios with CRC 0x400. If it doesn't work i will write as much as possible to fix it.

I successfully flash vbios with CRC 0x400 to my card, when it requeres CRC 0x800 and CRC of my card is 0x400 again But it is estetical only, CRC haven't effect for card stability or perfomance.

Sorry for my english (i am from Russia) ajacent values it is same voltage values in vbios, identical voltage values are arranged adjacent to each other. For exaple (in your vbios):

I use Free Neo Hex Editor. I can try changy some voltage values, but I'm not sure it's safe. If the replacement of certain values ​​does not help, then you need to change the adjacent values

If you follow the guide, you will not have any problems

I looked at you vbios, it seems that everything is done right, but try this (1.0volt) i try to overclock your vbios later 6990m_undervolted.zip

vbios stored on dGPU bios chip

Can you post your modified vbios ROM file?

there is nothing to worry about. My CRC was changing too (Current CRC 0xC700) only after few flashings of overvolted vbios. I just corrected the required CRC. We can't change CRC to first state (possible only when flashing the factory vbios with disabled CRC checking with ATIwinflash, but it's impossible, only atiflash for dos can skip CRC checking)

Your values is identical with my guide:

Where you get this vbios?Can you backup your current vbios with atiwinflash?

Hm, I realized. First state in my guide (for 3d-perfomance mode) it is voltage for Boost mode (absent in our model), second state it is 3D-mode for gaming and etc, and it haves 1000 value (1.0v).It is therefore likely to Dell vbios for HD7970M changed both values.