How To: vBIOS edit your HD7950 Vapor-X

[Ket]

This is a guide on how to edit your Sapphire Vapor-X HD7950 Video BIOS, as I figure out more then this will be added to. While the guide is specifically for Vapor-X Boost edition HD7950s the guide is also good for other 7950s or 7970s but values will more than likely be in a different place. This guide has been based on vBIOS 15.25.99, the values and positions of them within your specific vBIOS could and probably will vary depending on PCB revision, memory your card uses etc so some manual legwork will probably be required.


Editing voltage and ASIC / VRM signal

Before we begin theres some important notes to remember;

* Hex in the vBIOS is written BACKWARDS
* If trying to figure out some values for yourself remember (for example) 4004 [0440] is actually input as 440 into a programmer (such as the windows calculator when in programmer mode) which is 1.088v.

Take a look at the image below,



This is the first of TWO voltage tables, refer to the legend above for explanations of the colour coding. I’m not totally certain why there appears to be 2 idle voltages but I would guess one is boot voltage the other 2D voltage. I’m also not certain why there would seem to be 4 entries for DVD / Blueray playback voltage but as these voltages don’t need to be touched anyway its not something we need to be too concerned about. The load voltages is where things get peculiar, the voltage will bounce around anywhere between 1.023v and 1.188v, this certainly won’t help VRM temps and balancing these voltages should reduce VRM temps under load. As these voltages are all 3D voltages you may as well set them all to one value. If you have a high ASIC quality (75%+) then anywhere between 1.075v and 1.106v should be sufficient to reach in excess of 1100MHz GPU core speed. If you have a “average” to poor quality ASIC (65% - 50% > ) then 1.175v – 1.25v should be enough to net you 1100MHz+.

Now have a look at the following image;



This is the second of the voltage tables and in the case of Boost edition cards would seem to be unused but you may as well edit it anyway just in case. If this table isn’t used in Boost edition cards I really have no idea why it is still present in the vBIOS but my guess would be simply sloppy / lazy programming.

Lastly, have a look at this image;



Do NOT mistake this for a GPU voltage entry! You will brick the card and have to resort to the backup ROM chip to restore a "good" vBIOS.


Editing power limits

This step is much shorter than the last. By default you can adjust power limits to +20%, but that may not be enough to prevent the card throttling in some situations depending on voltage and clock speed. To change this limit simply adjust the following highlighted value;



Here I have adjusted the power limit to +50% (hardware limit), if I have read the vBIOS right this means the board will supply a maximum TDP of 351 when the power limit slider in CCC is set to +50% as [EA] in decimal is 234, but the cards lower power limit will remain unchanged. To deliver even more power to the board (bad idea..351 is huge) we will need to individually edit minimum and maximum TDP limits. The advantage of doing this means you won't even need to adjust the power limits slider every time you install a new driver.



If I have read the vBIOS right, the image above shows minimum TDP has been increased from 139 to 175, while the max TDP [EA] remains 351 when the power limit slider is increased to +50%. With this all in mind, below is a image of what I ended up editing power limits to;



You can see here that power limits should now be 175 minimum, 234 maximum and with the power limit slider to +20% in CCC a upper limits TDP of 280.


Editing memory voltage

This is by far the biggest thing for Vapor-X cards as most of them seem to use Hynix memory and only have 1.5v set.. or in other words Sapphire didn’t want to give you a chance at having a fair shot at getting a decent memory clock.

Check out the image below;



From the image above you will see the default memory voltage of 1.5v, for 1.6v change the highlighted [DC 05] to [40 06]. I won't show you how to edit memory voltage higher so you all don't go blowing your memory chips up by throwing 1.7v - 1.8v+ at them.

Thats it for now, I'll look at clock speeds and fixing the checksum which needs to be done as a result of changing clock speeds soon. Its VERY IMPORTANT to note all of this info I have pieced together simply by looking at the vBIOS in my Hex editor (HxD) and thus far have not tested all of my findings (memory voltage and manually changing board minimum / maximum power limits) so some of the info may be slightly inaccurate. If anyone KNOWS something is inaccurate (not just thinks it might be) then let me know so I can make the changes.

If you want to start looking at how to cool your hothead VRMs then visit THIS thread.