*** Tutorial: Advanced BIOS Editing with Maxwell Bios Tweaker ***
Tweaking The Voltage Properly: Getting The Voltages Right All Across the Voltage Table
I am posting this since I haven't seen the "proper" way to do this yet. It took me a long time to figure this out.
One problem with MBT and the normal way of BIOS editing by setting the max stable clock at the last position in the voltage table 74 is that down-boosting for some odd reason will not function properly, at least not in the upper clock ranges, such as 74 down to 63. It seems that Kepler & Maxwell still want or expect their max CLK in the voltage table entry where the card is boosting to at default.
If you use the ENTIRE voltage table for your tweak as is often suggested, when down-boosting it basically "skips" the upper CLKs and (in simple words)...jumps way too low to the next entry with a lower voltage which is already in the 60s CLK range. What I wanted is to make a BIOS that not only holds an OC at desired voltage, but ALSO can boost down properly so it decreases the volts when it would need to. (OF COURSE, the card won't even throttle in a game since the main goal of our BIOS is of course keeping a stable overclock WITHOUT throttling. But I wanted BOTH, an overclock bios and proper throttling and proper voltages all across the CLKS, say if I force the card by setting lower power target. Here are my findings.)
You should have an idea of your max stable core clock and what voltage it needs. For testing I am using Heaven Benchmark on Ultra/Extreme, Firestrike, 3DMark06, 3DMark11.
Don't assume you need the max. voltage your card (VRM) can give to get your overclock. My card is an EVGA SC ACX2.0 which is limited to 1.212V. However, for my desired OC of 1506 I can go as low as 1.187V and this with a rather poor ASIC of 70%. When the voltage is tested (see above) there is no reason to choose higher since you will only use more heat, power, the card will throttle earlier etc..etc.
For my example I am using my desired OC of 1506 and my max. voltage of 1.187V.
* Here comes what is different to other Bios modding tuts:
Test your card at stock and stock bios and establish what its default max. boost clock is. For this you can use GPUZ, the render test, or any other test WHERE YOU KNOW IT DOESN'T THROTTLE. You want to know the max MHZ your card boosts at and at what voltage.
* In my case (and for many cards), they will likely boost anywhere from CLK 62 to CLK 70. A card with ASIC 70% for example will go to CLK 63, a card with ASIC 72% will go to CLK64.
* Look at your default max boost, say it's 1367. You look this up in MBT in the Boost Table
and see 1367 is CLK 63.
What we do now, we're actually shifting our Boost Table in MBT so that our CLK 63 becomes our maximum, desired boost clock/overclock, like so:
In the "Common" Tab in MBT you set 1506.5 as Boost Clock and in the "Boost States" tab you specify your 1506.5 as well (see pic). (With most cards 1506.5 is actually already the maximum in the table, but it's possible your max. stable OC is less...or more. Then of course you use your number. I use my 1505.5 here since I tested this freq.
Switch to the "Voltage Table" tab in MBT. Now it's where it's getting interesting.
Since we shifted our entire boost table 11 or more notches "up", we need to adjust our voltage table.
You can ignore all the lower CLKs, the shifted boost clocks only affect clocks 35 and downwards.
Since our max. stable clock is at CLK63 (and not at 74 since we want to have the card "proper" boosting down if it would need to) we set everything from CLK 64 and down to 74 to a "crazy high" value like 1600. This, and the limit we specified earlier in the "Boost States" tab makes sure the card will never go beyond CLK 63.
Getting the voltage table right (from our max CLK with our max overclock down "upwards" upto CLK 35 sure is a thing I could write a book about. I must have tested here for weeks. But I found the "easiest" way is actually the best way to do it:
* FIRST, make sure that all values in the voltage table that are higher than your max. desired voltage ARE changed to your max. desired voltage.
In your voltage table, there will be many sliders on the right going up to 1281.3 or higher even. Change all those to 1187.5
(This is important since when the values exceed your max. voltage the card won't use the entry)
(Setting your max voltage BELOW your max.possible voltage also has the advantage that your card won't ever throttle due to voltage limit! As I mentioned earlier, it has several benefits NOT using your absolute max. voltage and is usually not even needed!)
Now, we're already ignoring all those at the bottom which I set to 1.600V since we don't use anything beyond CLK63.
Now you adjust the sliders on the LEFT, the so called "entry voltages".
CLK 63, your last valid entry in the table I set to 1.187V - 1.187V (both values the same).
Now you go upwards on the left and while you go up, with each step you decrease the left slider by ONE NOTCH.
This is why I said "easy" since this is easier than figuring out some elaborate curve. You simply go up the table on the left, one value less with each step and you do this from 64 upwards to and including CLK35. (Everything above ignore again since we only shifted boost CLKS which go from 35-74)
(I found only one little notch better than a steeper curve since with a steeper curve you might end up supplying CLKs at the lower end not enough voltage. Just going up and one notch less each time seems to be just right. As said, this is a topic where one could write a book about
For the sliders on the right, note that the last 18 or so up from 63 are all at the maximum 1.187V.
(You can also look at your stock bios and imagine that we just shifted the entire boost table 11 notches up and can look at the default bios. In my case, in the stock bios, the last 18 entries are LARGER than 1.187V. And now we shifted it so entry 74 has become 63, entry 73 has become 62..and so forth. This so you understand sort-of what I did).
*** Last but not least, of course we adjusted our power limits in the BIOS as well. I don't go into detail there since this has been covered many times elsewhere.
If all went right, you now have a bios that will have your max. OC stable, without throttling....but it CAN throttle down properly if you want to. Say, you can test this running a Benchmark and then run the Benchmark at 100% , 90%, 80%, 70% Power Target etc. and you will see how it will decrease volts/clocks..and most importantly...IT WILL BE STABLE also at the lower clocks. With other ways to mod BIOS, it will not decrease voltages properly at higher clocks. I tested many times with max boost clock at CLK74, but was not satisfied how it downclocked without reducing volts)