(GTX 970/GTX 980): Why Bios modding is mandatory for most cards if you want a stable overclock - Overclock.net - An Overclocking Community

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(GTX 970/GTX 980): Why Bios modding is mandatory for most cards if you want a stable overclock

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post #1 of 57 (permalink) Old 05-01-2015, 05:55 AM - Thread Starter
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* I keep this post technical and assume that whoever reads this is familiar with Maxwell Bios Tweaker and terms I use, such as "voltage table" etc. This is really a post for modders.

I looked at LOTS of GTX 970 Bios and with a good number of cards you can not add more voltage externally, say with Afterburner.
One indication for this is the THIRD slider in MBT's "voltage tab" in the BIOS, When there is one fixed value and no range, it's an indication that you cannot add more voltage.

This means, with many cards, like from EVGA, ASUS, MSI etc. you find yourself in a situation where you overclock, say in Afterburner but CAN NOT add more voltage.

This is bad for some reasons (which I will explain), but there is also a fix for it:


You will know that cards, depending on many factors like ASIC quality, power target, load etc. will boost to a certain BOOST CLK in the boost table, depending on their default given boost clock.
(A lot of cards in the 70%-ish ASIC quality range for example boost to CLK 63 or CLK 64 in the boost table.)

Each CLK entry in the table has its assigned voltage range.

So for example, your card may have a default boost clock of 1316, so it boosts to CLK63. At lower load maybe to clock 60 or 58.

You may find your max stable clock is 1500, so what you do in Afterburner you add 184 to the core.

But once you added core clock in Afterburner, the BIOS voltage table does not reflect the correct voltages.

You added clocks, say, equal to 10 or more boost bins to your card, but the card/bios does STILL USE THE SAME CLK BINS as if you were not overclocking.

Example: Normally, when your card would go to CLK 53 at stock, it might give you (example), 1.000V. But since you added a lot more (you're overclocking)...you would require a lot more voltage than what is specified in CLK BIN 53. (Again: the bios does NOT jump higher in the voltage table when you add clocks externally!)

What you need to do, you must specify your max. stable found voltage as the "default boost clock" in the BIOS and also make sure that the last entry in the boost table is this clock. (Say, 1506, or 1480, whatever you found stable).

By specifying your max. stable clock as "default boost clock" you force your card to the max. boost bin, all the way at the end of the voltage table. (And not, as would be default, somewhere in the middle, like CLK 63 or CLK64)

This is why you would not be stable with MANY cards where you cannot add voltages externally, you MUST modify the bios to get the correct voltages all through the voltage table.
(The instability becomes most apparent when the card CLOCKS DOWN, because it may be ok at your max. stock, default boost clock, say CLK63 and 1.200V, but then it boosts down and the individual voltages etc, are all messed up).

Of course, the best way is if you have a card which simply allows adding a bunch of volts on top of your OC (with Afterburner)...but as said MANY don't allow that.

Bios modding and flashing until the EEPROM smokes!! Yay!!
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post #2 of 57 (permalink) Old 05-01-2015, 01:35 PM - Thread Starter
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More findings:

MOST of the time, in your BIOS, the "boost table" (as seen in MBT) might be sufficient to cover all your overclocks.
(For example, my card makes 15xx "in games" but to get it really stable in extremely demanding benchmarks I choose 1481.0, the next one down from 1506).

The default bios boost table goes already up to 1506.

----> If your boost table covers your maximal attainable overclock (ie: The last value in the table, 1506 is equal or actually more than your actual possible overclock)
IT'S BEST NOT TO TOUCH THE BOOST TABLE. So do NOT shift the values in the boost table around.

---> Just put your maximum stable max overclock as "boost clock" in MBT. (In my case, stock boost clock is 1316. So I changed this value to 1481.0)

If you KEEP the default boost table it will automatically find the right voltages and will (depending on power limit, target etc.) use the same, correct voltages and clocks as a stock bios.

I did extensive testing on this just now and I confirmed that overclocking with Afterburner, WITHOUT the ability to add voltages is the worst thing you can do!
*** It gets worse: Overclocking with Afterburner actually DROPS voltages compared to stock ***

Short: If you have a card where you cannot manipulate voltages externally (those are many cards!) do NOT use Afterburner to overclock...but use a BIOS where you have your max. stable OC as "boost clock".

*** Here is an example what I mean

80% Power Target Test
1.150V clock freq 1329 < -STOCK bios no overclock, 1329mhz = 1.150V
1.125V clock freq 1406 <- card overclocked to 1480 with +140 in AB, now at 1406mhz, card gives only 1.125V (which is not enough!)
1.150V clock freq 1329 <- card where you specified 1480 in MBT as "boost clock", rather than using AB to add clock: The correct, sufficient voltage as with stock voltage for this clock.

This is also the explanation why many folks are complaining about instability at lower clocks! Because they use Afterburner to OC but their card (voltage regulator, that is) doesn't allow giving more volts with Afterburner. (Or they think they can but in reality their card doesn't take the voltage you set in Afterburner. I too can set AB to +50mv but it doesn't mean squat, it doesn't do a a thing to my voltages)

Bios modding and flashing until the EEPROM smokes!! Yay!!
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post #3 of 57 (permalink) Old 05-04-2015, 02:31 AM
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You are my hero!

Thank you so much for explaining!

So basically I just have o edit 1 value to fix this mess in MBT?

I've been looking for a low utilisation bugfix for months now...
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post #4 of 57 (permalink) Old 05-04-2015, 05:28 AM
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Thanks for this post. I have noticed this a great deal - specifically in WoW with 200% render scale - card gets nuked and likes to pull ~30-50w more than some other games. I power limit it to 250w (980) and cap to 200fps in-engine because i sometimes run that game 50 hours a week and there's no need for the noise, but in that game and several others, i've seen 2 choices:

1; max OC all the time, not hitting power limit
or
2; instability

this should fix it.
Quote:
I've been looking for a low utilisation bugfix for months now...

You're probably playing CPU limited games, etc. This shouldn't improve GPU utilization. What games and situations are you seeing GPU below 100% load at and what's the rest of your hardware and screen resolution/game settings?

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post #5 of 57 (permalink) Old 05-04-2015, 05:36 AM
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Quote:
Originally Posted by Cyro999 View Post

Thanks for this post. I have noticed this a great deal - specifically in WoW with 200% render scale - card gets nuked and likes to pull ~30-50w more than some other games. I power limit it to 250w (980) and cap to 200fps in-engine because i sometimes run that game 50 hours a week and there's no need for the noise, but in that game and several others, i've seen 2 choices:

1; max OC all the time, not hitting power limit
or
2; instability

this should fix it.
You're probably playing CPU limited games, etc. This shouldn't improve GPU utilization. What games and situations are you seeing GPU below 100% load at and what's the rest of your hardware and screen resolution/game settings?

No, it's not about that the utilisation would be a problem itself but when you OC the card with AB the voltage tables will shift and this may lead to instability at lower clock speeds even though you can run Unigine Heaven or Crysis for hours without problems.

I had this problem specifically with LoL for example.
The card didn't boost at all because of medium load and because the voltage tables were screwed up it would crash within a few minutes even with a mild OC while I could play BFH for hours!

I really hope this will fix the problem!
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post #6 of 57 (permalink) Old 05-04-2015, 06:16 AM - Thread Starter
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Quote:
Originally Posted by Geicher View Post

You are my hero!

Thank you so much for explaining!

So basically I just have o edit 1 value to fix this mess in MBT?

I've been looking for a low utilisation bugfix for months now...

Yes, with one caveat which I forgot to mention!

Change the "Max Boost Clock" in Default Tab to your max stable clock, say 1481.0

Now, it can happen you changed your Boost Clock to 1481.0, but your card still only boosts to, say, 1250.

Now, look over the voltage tab and , at the bottom, the last some entries might have voltages values which are a lot higher than your card can actually supply.
(In ALL Bios I looked at, the voltage tab I looked at, the maximum voltages in the voltage table is 1281.3 (Which is WAY too high, so the card won't ever boost there but only to the clock entry in the table which has the max voltage)

*** --> Edit all the values in the voltage table which are HIGHER than your actual card's max voltage to your actual card's max voltage. Those are a bunch on the right and a few on the left. This allows the card to use the entire voltage table.

I give you an example of my own card:




My card's absolute max voltage is 1.212V (many cards are limited to 1.212V), however my card is a special case since at 1.212V it may black screen in Heaven Benchmark. So I "artificially" limited my card to a max. voltage of 1.200V (It is stable at 1481 at 1.200V)

You see in my voltage table that I changed all the values which had been HIGHER than 1.200V to 1.200V. Means the card will now boost maximum to CLK72, WHICH IS ALSO THE ENTRY IN THE DEFAULT BOOST TABLE, which is 1481.1 <--- so they match up.

The last two clocks, CLK 73 and CLK74 I put in "crazy high values" so the card never uses CLK73 and CLK74, but CLK 72 as maximum.
(Also, don't forget in the "Boost States" tab to adjust GPC MAX for P00 and P02 to whatever your max stable OC although I dont think it's really needed. But its a good thing to do anyway)

This voltage table keeps essentially the same clocks/voltages as the default BIOS so the voltages are correct, also when it boosts down.

TLDR: Adjust the voltage table so your card uses the entire table, but essentially leave the original curve and increases of voltages and don't touch them. This is how I did it.

Bios modding and flashing until the EEPROM smokes!! Yay!!
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post #7 of 57 (permalink) Old 05-04-2015, 07:27 AM
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Quote:
I had this problem specifically with LoL for example.
The card didn't boost at all because of medium load and because the voltage tables were screwed up it would crash within a few minutes even with a mild OC while I could play BFH for hours!

I really hope this will fix the problem!

Yea, that should be due to this problem. Your GPU utilization itself wouldn't go higher (LoL is a graphically light and quite highly CPU bound game) but it should run at for example 1200mhz @1.05v instead of [email protected] (if you had a +100mhz offset) when it's not boosting up to your max OC.

Thanks a lot for this thread!

I don't believe in "good enough"~!!

240hz / gsync / low persistence is AWESOME

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post #8 of 57 (permalink) Old 05-04-2015, 07:50 AM - Thread Starter
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Just some additional notes:

Not all people who mod BIOS know actually what they're doing. So careful if you get/use some BIOS from somewhere else who modded it for you.

There can also be a problem that the card might not boost to its maximum because people modded their TDP and power targets to some insanely high values.

Say, if I were to mod my GTX 970 to a 500W TDP/Power limit or something.

Then there would be the problem that the card runs a game and of course never gets nowhere those way too high limits and then THINKS it doesn't need to boost because of "low utilitzation", in other words, upping power limit and TDP to crazy high levels does exactly the opposite.

What you want to do, if you mod a card and want to increase power limits, keep it REASONABLE, I always say 15%-20% more but not more.

As a rule, I run Heaven Benchmark and during the benchmark it should not throttle and maybe show 95%-98% usage. You should NOT mod your card so you run Heaven Benchmark and the card thinks it it's only at 50% usage...of course that would be wrong too.

My GTX 970 default, stock power limit is 170W, with 187W at 10% in the slider. I modded it to 196W as default (0%) and 206W with slider at 105%. 196W is a good value for THIS card so I keep it there. It already gets very hot 77C in Heaven BM since the ACX2.0 cooler is junk.

Bios modding and flashing until the EEPROM smokes!! Yay!!
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post #9 of 57 (permalink) Old 05-04-2015, 07:53 AM
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Yea almost.

An example for my specific problem:

The card would normally run at 1250 MHz at 1.0V for example. (without boosting!)

Now, after I apply any OC to the card it would still run at 1250 MHz (cause the card won't boost in this application or game) but because of the shifted voltage tables the applied voltage would be lower (depending on the offste clock you applied in Afterburner)

So after OC I would have only 0.95V at 1250 MHz for example. If I increase the clock speed even higher the voltage will drop at the same time.
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post #10 of 57 (permalink) Old 05-04-2015, 08:38 AM
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Dear flexy123, can you post your modded BIOS for your 970 ACX 2.0 that reflects your considerations in previous messages?
I think it will be easy for everyone to follow you with it opened in MBT.smile.gif

PNY GTX970 reference 81% with EK full waterblock
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