Max overclock in SLI lower than one card. Why?

[Michaeljcox24]

Not posted for a while lads but got a question...

I've got two 580 phantoms in SLI. If I disable SLI, then the top card will overclock to 940Mhz, stable. However, when I enable SLI, the max I can get is 870.

Is this because the bottom card is a worse clocker?

Also, for any of you lads running sli, do you put the same voltage through both cards? At the moment I have 'synchronize settings for similar gpu's' clicked in afterburner. Is this best practice?

Thanks

 

[Rusty0611]

My cards clock the same in SLI. No idea if it's different for the 5** series.

Well... One card clocks slightly higher (30 Mhz or so) and if I run in SLI then the faster card will still run at its highest OC setting.

 

[Michaeljcox24]

Just wondering if one card needs more to get up to 900, if it's common practice to bench each one separately to find out what voltage it needs.

 

[Rusty0611]

Yes you should try to find each cards limit/voltage requirement separately. It's no different to a CPU in that respect. One might be better quality silicon than the other.

 

[Michaeljcox24]

ok ta. will do. thanks a lot

 

[OptimaLnrg]

If you're ticking 'synchronise settings..' then you're also syncrohnising the clock speeds.

So likely the bottom card cannot make above 870 on the settings?

Or maybe I've misunderstood you.

Try untick the option and running the cards on different settings. You can select the active gpu (gpu you're editing for) by selecting it in the drop down box in the settings menu.

 

[Michaeljcox24]

Yes, you understood correctly what i was trying to say. However, i think ive got to physically unplug my monitor and plug it into the bottom card to bench it. Saves the hassle of stripping the cards out

 

[OptimaLnrg]

yes you should be able to leave them both in, disable SLI and dedicate one to physx, then bench the one you're after.

Just to find the max clock ofc.

 

[Michaeljcox24]

doesn't seem to work, when i plugged monitor into bottom card, I had no video output (even with sli disabled)