New to the Green team, 980Ti SLI questions

A

Aquineas

Limp Gawd
Joined
Mar 2, 2004
Messages
214
I noticed on my 980Tis there is a spot to run a cable to connect the cards on top, but neither of the reference cards I used have that cable in the box. AMD had done away with the need for a connector for XFire (starting I believe with the R9 generation) and that connection is no longer physically present on the cards.

(Running driver version 353.30)

My questions:
  1. Do I need to physically connect the cards I want to SLI together via cable? If so, where do I obtain such cable?
  2. If the answer to #1 is 'no', then how do I enable SLI in the drivers? I don't see any references to SLI in the control panel, which leads me to think I do need the cable
  3. I also spent picked up a 750ti on the cheap that I intended to dedicate for PHysX, even though that seems like a non-starter. Should I dedicate the 750Ti to Cuda, and should I also use the TIs for Cuda?

Thanks all
 
Yes you need an SLI bridge. You can buy them online or at various retail stores (Fry's/Microcenter more so than something like a Best Buy).

You should also check to see if your motherboard came with an SLI bridge. Look up the model number online and if the package contents include it, start digging through your boxes and find it.

I am not an expert with regards to Physx, but the general consensus I've read before is that it's not worth running a weaker card for dedicated Physx if you're already doing an SLI setup. The gains would only even be possible in a small number of games, and the extra heat + case airflow interruption from a 3rd GPU would probably offset any gains by making your SLI cards clock lower (or have a lower OC limit at the very least) due to the higher temperatures.
 
I never got to testing the performance of my 750Ti for PhysX when I ran 2x980 Tis, but I did when I had 2x 780s, and it did help (mostly for min and somewhat for avg fps).
 
The amount of PhysX games is still fairly limited so I'd probably skip the 750Ti.
 
If you are using the sandy bridge chip in your signature, I would definitely skip the third card. You only have 16 lanes of PCIE 2.0, so with SLI 980 tis they are each running at 8x. My understanding is that if you throw in that 750ti, the 750 and the second 980 will both run at 4x.
 
Your motherboard should have included it.

bI4tPFP.jpg
 
QuiteSufficient said:
If you are using the sandy bridge chip in your signature, I would definitely skip the third card. You only have 16 lanes of PCIE 2.0, so with SLI 980 tis they are each running at 8x. My understanding is that if you throw in that 750ti, the 750 and the second 980 will both run at 4x.
Click to expand...

According to the spec sheet on Newegg:

4 x PCIe 2.0 x16 (single @x16, dual @x8, triple @x8, x16, x16 )

Running three cards in the PCIe 2.0 x16 slots will still be fine.

Even ASUS says the board supports three-way SLI.

https://www.asus.com/ROG_ROG/MAXIMUS_IV_EXTREME/specifications/

So it will be fine running a 750Ti as a PhysX processor.
 
Aquineas said:
I noticed on my 980Tis there is a spot to run a cable to connect the cards on top, but neither of the reference cards I used have that cable in the box. AMD had done away with the need for a connector for XFire (starting I believe with the R9 generation) and that connection is no longer physically present on the cards.

(Running driver version 353.30)

My questions:
  1. Do I need to physically connect the cards I want to SLI together via cable? If so, where do I obtain such cable?
  2. If the answer to #1 is 'no', then how do I enable SLI in the drivers? I don't see any references to SLI in the control panel, which leads me to think I do need the cable
  3. I also spent picked up a 750ti on the cheap that I intended to dedicate for PHysX, even though that seems like a non-starter. Should I dedicate the 750Ti to Cuda, and should I also use the TIs for Cuda?

Thanks all
Click to expand...

1. Yes, SLI bridge. Ebay/Amazon/HardForum F/S Thread
2.skip
3. Unless you are playing Physx Games, Batman, Assassins Creed, Borderlands, I would not use one. The power of two 980ti's should be more than enough anyway.
 
Thanks again for the replies folks. Yeah my sig has been outdated for a while now. My Maximum Extreme MB failed a while back so I replaced it with an Asrock z87 OC formula along with a i7-4770K. My most recent graphics cards were dual 290Xs, bought the day were available for sale.

With regards to the SLI cable, I did pick one up from Fry's and I swear it looks a lot like the old Crossfire cables which I have a ton of laying around the house; it would be interesting to see if they were the same (which doesn't really matter because I have too many old PC parts in too many boxes in too many parts of the house. One of these days I'll get around to consolidating it all and throwing out most of it, as it's functionally useless anyway if i can't find something I'm looking for.).

As for the 750Ti and PhysX, I knew it had limited use, but as a longtime red-team member I have been seeing the PHysX hype for so long that I finally wanted to see it in action for myself. I guess it really is just hype with so few games, but que sera sera.

Back to the original point, I got the cable and connected them but still don't see a PhysX entry on the control panel. I wonder if it's because I have one of my monitors plugged into the Dual DVI on the second 980Ti (I have a 3x1440p setup). I'm going to switch some of the connections around and see if it makes a difference. I'm also wondering if the 750Ti is confusing things a bit.
 
Aquineas said:
Thanks again for the replies folks. Yeah my sig has been outdated for a while now. My Maximum Extreme MB failed a while back so I replaced it with an Asrock z87 OC formula along with a i7-4770K. My most recent graphics cards were dual 290Xs, bought the day were available for sale.

With regards to the SLI cable, I did pick one up from Fry's and I swear it looks a lot like the old Crossfire cables which I have a ton of laying around the house; it would be interesting to see if they were the same (which doesn't really matter because I have too many old PC parts in too many boxes in too many parts of the house. One of these days I'll get around to consolidating it all and throwing out most of it, as it's functionally useless anyway if i can't find something I'm looking for.).

As for the 750Ti and PhysX, I knew it had limited use, but as a longtime red-team member I have been seeing the PHysX hype for so long that I finally wanted to see it in action for myself. I guess it really is just hype with so few games, but que sera sera.

Back to the original point, I got the cable and connected them but still don't see a PhysX entry on the control panel. I wonder if it's because I have one of my monitors plugged into the Dual DVI on the second 980Ti (I have a 3x1440p setup). I'm going to switch some of the connections around and see if it makes a difference. I'm also wondering if the 750Ti is confusing things a bit.
Click to expand...

http://www.overclock.net/t/1292546/crossfire-and-sli-bridge-the-same

heh just found that quick for ya.

Put all monitor cables on the same card.

In control panel, select the 750ti as physx
 
Man I finally got SLI to work. For some reason, I could not get SLI working with my Xonar DX add-in sound card plugged in. Ah well back to motherboard sound I guess. Very odd incompatibility. It's unlikely it's a power supply issue; I have a 1300W continuous power supply and besides, all the cards showed up in the Nvidia control panel, they just weren't SLI enabled. Thanks again for the links and the help.
 
^
Sounds like you ran out of PCI-E lanes, I'm guessing you had to plug in the sound card into one of the x16 slots because of the GPU spacing?. SLI requires that all cards have a minimum x8 link (regardless of PCI-E version) or you just cannot enable it, and since you plugged in a third device, you took a card out of x8 mode and that's why you couldn't enable SLI. You would've had to run the sound card in a dedicated x1 slot to avoid that.
 
You know that actually makes sense; that's gotta be it. I played a few minutes of The Witcher 3, ultra everything with hairworks turned on in 1440p. Buttah smooth in most places though it did slow down a bit in Novigrod. Definitely a pretty big jump over my X-Fired 290x's, but that shouldn't come as a surprise. 2D seems a little slower but it's no big deal. Cards are definitely cooler and quieter than the 290x's (which also shouldn't be a surprise to anyone).
 
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It looks like your motherboard has a PCI-E x4 slot on the bottom. You should be able to plug your sound card in there, as it's controlled by the PCH.
 
Aquineas said:
Man I finally got SLI to work. For some reason, I could not get SLI working with my Xonar DX add-in sound card plugged in. Ah well back to motherboard sound I guess. Very odd incompatibility. It's unlikely it's a power supply issue; I have a 1300W continuous power supply and besides, all the cards showed up in the Nvidia control panel, they just weren't SLI enabled. Thanks again for the links and the help.
Click to expand...

I have the same sound card and I have no problems with running up to 3-way SLI with it. May want to make sure the power plug is plugged into the front of that card (and that it is secure).
 
kasakka said:
The amount of PhysX games is still fairly limited so I'd probably skip the 750Ti.
Click to expand...

I would skip it too, but not because of a lack of games. There aren't a ton, but there are quite a few that benefit from it visually. However, even at full settings in most of the games, you won't need an additional card. As just one example, with PhysX on high, on my single 970, Borderlands 2 (which granted is a little older) simply flies.

Maybe build a little living-room gaming PC with that 750Ti. It's more than sufficient to play games at 1080 (assuming a 1080 TV of course) with decent settings.
 
My physx has always been slow on my systems for some reason. Even running 4-way Titans and now 3-way 980TIs. Anytime the "fluid" shows up my 180fps scene goes to about 36fps for about 5-8 seconds. Never figured that out.
 
clayton006 said:
I have the same sound card and I have no problems with running up to 3-way SLI with it. May want to make sure the power plug is plugged into the front of that card (and that it is secure).
Click to expand...

it definitely wasn't a power connection issue to the sound card because the system could see the sound card just fine, and could also see all the video cards (2x980ti and 1x750ti). Also on my card at least, if you don't plug in the auxiliary power, it makes a horrible beeping sound that's about as annoying as a smoke alarm going off. I'm pretty sure the other poster nailed it, and it's likely a limitation of the Z87 OC Formula. My original Maximus IV Extreme was able to handle the PCI traffic but as I said it died somewhere along the way, and I didn't want at the time to spend another $370 on an equal caliber replacement MB (which is what it cost new back then).
 
clayton006 said:
My physx has always been slow on my systems for some reason. Even running 4-way Titans and now 3-way 980TIs. Anytime the "fluid" shows up my 180fps scene goes to about 36fps for about 5-8 seconds. Never figured that out.
Click to expand...

Yeah it kinda sounds like PhysX is a dud. I guess with me being on the red team for so long and going with Nvidia for this generation, I finally was excited to see what I had been missing. It turns out, not much :-(.
 
Aquineas said:
it definitely wasn't a power connection issue to the sound card because the system could see the sound card just fine, and could also see all the video cards (2x980ti and 1x750ti). Also on my card at least, if you don't plug in the auxiliary power, it makes a horrible beeping sound that's about as annoying as a smoke alarm going off. I'm pretty sure the other poster nailed it, and it's likely a limitation of the Z87 OC Formula. My original Maximus IV Extreme was able to handle the PCI traffic but as I said it died somewhere along the way, and I didn't want at the time to spend another $370 on an equal caliber replacement MB (which is what it cost new back then).
Click to expand...

Never had mine beep but yeah that sounds like the board could have been the problem there.
 
Aquineas said:
Yeah it kinda sounds like PhysX is a dud. I guess with me being on the red team for so long and going with Nvidia for this generation, I finally was excited to see what I had been missing. It turns out, not much :-(.
Click to expand...

It may be game specific as well. Borderlands 2 and Pre-Sequel I have those problems with. The Batman games (save Knight because I haven't played it yet) I had no problems with physx.
 
In the Arkham games I get around a 15% boost to framerate with a dedicated PhysX card. I don't really see any difference in other games like Borderlands 2. What is noticeable, though, is that accelerated effects react in a less "glitchy" manner with a dedicated card than without one.
 
I've got a single GTX 970 on a 4690K system. The effects in Borderlands 2 at highest PhysX settings are perfectly fluid and not glitchy at all. However, it's a fairly new (and still clean) build. One thing that I've seen cause some serious problems is older PhysX drivers hanging around from game installs (that sometimes include it) etc. If you're seeing problems, I'd uninstall just the PhysX driver, grab the latest, and try again. (even if you don't update to the latest video driver) There's no reason multiple cards shouldn't work perfectly with something like BL2.

This was a long time ago, but when I had a GTX 295, it shared the PhysX load flawlessly between GPUs with SLI in whatever I was playing at the time. (probably Mirror's Edge, or maybe Metro or something like that)

I have run into issues since that were completely resolved by wiping and reinstalling the PhysX driver though. It's worth a shot anyway.
 
I would think a 750ti for Physx would slow down 980ti's or Titan X's.

Also, Nvidia is trying sneak away the option to offload Physx, like in Witcher 3. It will not use a secondary Physx card. Only primary!
 
As another recent 980ti purchaser, does SLI still require identical cards? Or has that gotten more lax?
 
jackstar7 said:
As another recent 980ti purchaser, does SLI still require identical cards? Or has that gotten more lax?
Click to expand...
It still requires identical cores, so a 980 Ti can't be matched with a standard 980. You should be able to mix and match brands, but you should try to keep specs as close as possible to avoid potential issues. Power states, for example, are much more sensitive with Maxwell than it was previously, so I wouldn't try matching a reference card with say a Galax HOF or Gigabyte G1.
 
Thank you. I'll keep a long-term eye towards another G6 then if a point comes where I can pick one up for a song, then I might go for it.
 
You could always flash the same bios on both and make them identical :) But yea, it works with all of them. They will run at the slower card's clocks though i think.

Aquineas: did you try 3d mark firestrike test 4 (combined test) ? What do you score in there with sli and what gpu usage % are you getting during the test?
 
I'm getting between 7404 (http://www.3dmark.com/3dm/7651356) to 7488 (http://www.3dmark.com/3dm/7651470) on the combined score. The first number is with the 750Ti disabled completely and one 980Ti set as the Cuda device (non-dedicated PhysX), the second number is with 750Ti as the Cuda device and dedicated to PhysX. I got 5462 using the 290X pair. The 290X pair is roughly 27 percent slower.

Batman Arkham Origins Numbers. Using the following settings for all except where noted:
Code: 
2560x1440
V-sync off
AA: GeForce TXAA High
Geometry Detail: DX11 enhanced
Dynamic Shadows: DX11 Enhanced
Motion Blur: on
DOF: DX11 Enhanced
Distortion: On
Lens Flares: on
Reflections: On
Ambient Occulusion: DX11 Enhanced
Hardware Accelerated Physx: High

(750Ti dedicated to PhysX)
High:170
Low:68
Average:102

(using 980Ti one set to Cuda, non-dedicated)
High: 129
Low: 63
Avg: 88

(CPU only, Hardware Accelerated PhysX set to "Normal" in game)
High: 238
Low: 28
Average: 134
 
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