P870DM-G 980Mx2 no SLI?

Hope this is an appropriate place to ask for help...

I picked up one of these bad boys with dual 980Ms (Sager branded, through XoticPC) at launch, and did nothing with it for a few months as I was moving to Japan. When I settled down and started to use it seriously, however, I was slightly disappointed by the performance, but couldn't figure out why. Today I finally found out: my cards aren't running in SLI. I must be the dunce of the year to not notice this months after I bought the PC, but it didn't even occur to me to check. The system profiler showed two cards, the Nvidia driver didn't give me any errors as I was installing, so...it just never occurred to me.

My question, though, is: what could be wrong? I'm on stock everything--bios and vbios, the cards have the same version vbios, and I've taken the case off to confirm that there is an SLI bridge cable installed, and it's snug on both ends.. I've clean reinstalled the Nvidia drivers a few times and...nothing. Am I missing something boneheaded here, or should I be worried about defective components?

I've included a screenshot with as much relevant information as I could cram into it. Pretty obvious from the 3DMark alone score that it's only running on one GPU. Anyone got any ideas?

 

Could always try a program called differentSLIAUTO.

nVidia drivers have been rather buggy lately. Esp with SLI.

 

Just tried it, no effect.

I wonder if the bridge cable is bad...both cards seem to be OK by themselves. I guess I'll get myself some thermal paste and take off the heatsinks, just to check...

 

Did you actually enable sli inside the nvidia driver? Is the driver showing sli capable available?

 

Yeah, that's the thing: the driver has no SLI option where it should be. It's usually under the PhysX/Surround menu, right? Driver shows the two cards clearly enough, but no SLI option.

In the mean time, I took the heatsinks off and flipped the bridge cable around. Didn't change anything either.

 

Faulty cable does seem to be the most likely option. However its not exactly certain either. Lot of issues like this lately.

 

Well...I fixed it. Some combination of taking both cards out, swapping them, reinstalling the drivers, and realizing that the SLI bridge cable had come from the factory with the end marked "Slave" hooked into the card in the slot marked "Master" fixed it. Now I really should turn this poor kid off until I re-paste everything, since card 2 is idling at a toasty 83 degrees .

Thanks for the help, everyone.

 

I'm glad you were able to get the SLI issue resolved. If you ever have questions and need help with anything, don't hesitate to reach out to our tech support or myself. We'll be glad to help out. Let us know how everything is running once you re-paste it as well.

 

Do SLI cables actually have a polarity? CFX cables don't.

 

I don't think they are, it's likely the reseating did the job.

 

Unfortunately my methods weren't the most scientific, so I can't say for certain whether it was the cable or the re-seat that fixed it. All I do know is that one end is definitely marked "Master," and the other "Slave," and the motherboard has corresponding markings as well (I think the left card is master, facing right side up), and my card had the "Slave" end plugged into the master card. There are some pictures of it on this site even (from this thread: http://forum.notebookreview.com/thr...ermal-paste-replacement.789825/#post-10227197)

With how buggy everyone says the drivers have been, though, I wouldn't be at all surprised if a re-seat was all it took. Or in my case a swap.

 

The cable is bent in a certain way to make it sit properly, it's not something I have checked out on mobile cards though.

 

Actually, on this model, the cable is completely reversible. You can bend either head up to seat it right. If it weren't for the markings, both sides would be identical. I'd just rather do what the labels tell me though . I can't think of any reason why it would be polarized, but...who knows what evil lurks in the hearts of Nvidia?

 

Bending the cable back and forth each time you are swapping them though is a bad idea