SLI Overclocking

[HappyChubbs]

Hello everyone,

 

I am trying to overclock my two 680's in SLI and I have two questions.

 

Is it normal for both cards to have two different clocks when being pushed?  If so, do I need to set the offset accordingly so they can match? As you can see in the image, GPU1 is at 1097 and GPU is at 1084.  Even with sync on they are not in sync (Unless I am misunderstanding the term sync).  GPU-Z is also showing them at different clock.

 

 

Reference I used for overclocking.

http://www.overclock.net/t/1265110/the-gtx-670-overclocking-master-guide 

 

 

 

[Judahnator]

If you leave them both at auto, they will do the rest on their own. Usually, there are no problems due to a little bit of buffer.

 

If you are not having any problems, id just let it alone

[VSG]

Looks like you have fallen prey to Nvidia's +13 clock bin for Kepler. Read up more here: http://www.overclock.net/t/1438886/official-nvidia-gtx-780-ti-owners-club/1950_50#post_21193640

 

Essentially your second card is not exactly stable at 1097 MHz core under those conditions (combination of temperature, power limit, core voltage- I can't saw which one exactly at this point) so it downclocked automatically to the next lowest +13 bin which is 1084. If you had chosen 1096, that card would still likely have gone down to 1084 as seen by that table in the linked post.

[HappyChubbs]

 

Essentially your second card is not exactly stable at 1097 MHz core under those conditions (combination of temperature, power limit, core voltage- I can't saw which one exactly at this point) so it downclocked automatically to the next lowest +13 bin which is 1084. If you had chosen 1096, that card would still likely have gone down to 1084 as seen by that table in the linked post.

 

So the card will not be stable at all with higher clocks?

[VSG]

I can't say that because I don't know anything about your system. 1.15 V is quite low so it may well be a voltage starvation for the second card. If you can, run each card separately and see how high they can overclock.

[HappyChubbs]

I can't say that because I don't know anything about your system. 1.15 V is quite low so it may well be a voltage starvation for the second card. If you can, run each card separately and see how high they can overclock.

 

Guess I will try that.

 

The motherboard is an Asus Maximus V Extreme and a Seasonic 1000W Power Supply.  I hope it's not a power starvation, because that is as high as I can make the Voltage go.  It gets pushed to 1.175V.  And the OverVoltage button does not do anything.

[Blecter]

It is normal for clock speeds to be off. Cards running in SLI do not have to run at the same speeds. Not all cards run at the same clock speeds from the factory either. One of my 760's runs 13MHz slower than the other from the factory.

Sync on Precision X doesn't sync the cards to the same speed - it syncs the amount each card is overclocked. This means that if you add +30 core on card one, it will automatically add +30 core to the other without you having to go in and manually change it.

Obviously one card won't clock as high as the other, so if you do all your stability testing with the cards sync'd then you are limiting your overclock to that of the weaker card. You can overclock your cards independently (NOT in SLI mode) to find each maximum overclock, then use that info to set both overclocks independently for use in SLI (then retest/adjust for stability). In the end you'd still have one card clocked higher than the other for maximum overclock, as chances are one card is stronger than the other.

[Leonard]

Are you typing the figures manually or using the slider? Sometime the slider is very hard to control.

[HappyChubbs]

I type it in manually.  I am not delicate enough to move the slider.