2 graphics in SLI + one not in SLI

[DrDinger]

Hi,

Thanks everyone for having a look at my query.

I am running:
Gigabyte Z97X gaming 5 mobo
4 x 4GB DDR3 Ram @ 1600mhz
Intel i7 4770k @ baseclock (it doesn't seem to like being overclocked)
2 x GTX 980s in SLI
1 x Intel 180GB SSD
3 x other HDD (1gb + 2b + 4gb)
Samsung U28D390D UHD monitor
Windows 10
Rest of hardware probably not important.

Currently the graphics cards, I think, have 8x PCIe lanes each and are in SLI. I am luckily able to game with this setup at 4k 60fps.

I have a Zotac GTX 760amp which I could pop into the 3rd PCIe slot, but I am aware this will make the PCIe lanes 8x 4x 4x. I'm not sure if this will slow down the overall setup because less lanes are available to the high-end 2-way SLI cards?

What do you think?

DrDinger

 

[RCFProd]

For what purpose is your intend to use the GTX 760? For Physx?

 

[Dunlop0078]

I dont think it will slow it down however I doubt it will add much either, what power supply do you have? Are you sure it will even power 3 of them? You play at 4k with 760s? How does it run is their rampant stuttering and micro stuttering? You must be using well over 2gb of vram, I use over 2gb in gta v at 1080p.

 

[RCFProd]

I dont think it will slow it down however I doubt it will add much either, what power supply do you have? Are you sure it will even power 3 of them? You play at 4k with 760s? How does it run is their rampant stuttering and micro stuttering? You must be using well over 2gb of vram, I use over 2gb in gta v at 1080p.

Sounds like you might have made a mistake reading. He wants to run 2x GTX 980 with an additional GTX 760, which for gaming won't work since you can't pair 2 different graphics cards in one system obviously. So if it is for gaming it won't work, you need 3x of the same GPU's for that.

 

[RobCrezz]

your SLI will disable.

SLI requires 8x at a minimum.

 

[Onefurrybanana]

I think your better off with just 2 980s. Physx really only helps in a few games and the extra power draw and hear isn't worth it. And as you stated it will slow down the pcie lanes which i think would only cause you to lose performance. Im not sure you can do sli in x4 i believe only crossfire can do that

 

[sizzling]

PhysX also requires a gpu not much weaker than your main display. I'd expect a 760 when working as PhysX would actually hold back sli 980's. If your PSU is up to it (good 900-1000w) then no harm in trying

 

[JackNaylorPE]

You most certainly can use a different card for PhysX. You can not SLI the 760 with the other cards but using an older, less powerful card is exactly what is recommended by nVidia for PhysX.

However, with your MoBo, SLI would be disabled unless your MoBo was equipped with a PLX chip You would need to get a Gigabyte SOC Force for Z97 or move to the X99 platform to pursue this route. You have only 16 PCI-E lanes available, now being used in a x8 x8 configuration. Adding a lesser card for PhysX as per nVidias recommendation, is a valid choice, hoiwever, by inserting anything at all in the 3rd PCI-E slot, the configuration changes to x8 x4 x4. It's that 2nfd number that is the problem because nVidia cards requires x8.

PhysX adds a whole lot to the gaming experience but it's one of those things that ya don't really notice until you turn it off. The power draw is insignificant, the card itself draws a max of 170 watts and it wont do that just doing PhysX.

The PEX chip provides the extra PCI lanes as does a 5820k (28 lanes) / 5830x (40 lanes). Since you only have 16 , that's what is stopping you.

The 760 is more than powerful enough to handle the twin 980s. When PhysX was first incorporated, the recommended card was an old 8800. FiringSquad had a great article on the subject using various card combos but the site no longer exists.

http://www.tomshardware.com/reviews/batman-arkham-asylum,2465-11.html

The good news here is that a GeForce GT 220 can be had for as little as $65 online, and as a dedicated PhysX card, it will guarantee that the High PhysX setting won't bottleneck performance. Even at 1920x1200, the GT 220 produced a minimum frame rate of 36 FPS as a dedicated PhysX card. Using more expensive solutions as dedicated PhysX processors didn't produce appreciably higher frame rates, so the GeForce GT 220 is a real PhysX champion for the price.

So while cards have progressed enormously since these days, the dedicated PhysX card recommended for $400 main cards back in the day was only a $65 card and spending more didn't bring any higher frame rates.

 

[Dunlop0078]

I dont think it will slow it down however I doubt it will add much either, what power supply do you have? Are you sure it will even power 3 of them? You play at 4k with 760s? How does it run is their rampant stuttering and micro stuttering? You must be using well over 2gb of vram, I use over 2gb in gta v at 1080p.

Sounds like you might have made a mistake reading. He wants to run 2x GTX 980 with an additional GTX 760, which for gaming won't work since you can't pair 2 different graphics cards in one system obviously. So if it is for gaming it won't work, you need 3x of the same GPU's for that.

Oh yeah oops. I though he was talking about sli 760s for whatever reason.