Not sure if this belongs in the motherboard or GPU forum section. I posted in both a moderator can delete the one in the wrong forum section.
System info :
EVGA X99 Classified E-ATX motherboard
Intel 5930k custom water loop
16gb G. Skill 2666 DDR4 RAM
EVGA SuperNova P2 1000w power supply
2x EVGA 980ti Classified


I installed 2x EVGA 980ti Classified GPU's a few weeks ago. They are installed in slots 1 and 4 EVGA's product manual says these are the proper slots for 2way SLI on this board and they should be x16/x16 with the 40 PCI-E lanes from the 5930K. I have the extra 6 pin power plugged into the motherboard for the PCI-E slots. For some reason slot 1 is reading 3.0 x16 but slot 4 is reading 3.0 x8. Why is slot 4 x8 and not x16 like it is suppose to be?? Is it that the GPU just can't use the bandwidth ? I tried pushing the cards with Heaven benchmark, 3d Mark, Furmark and it stayed at x8. I have tried disabling the other PCI-E slots. I have both the m.2 slots disabled. I have no other hardware in any other PCI-E slots. I also noticed that in the Nvidia LED configurator that the card in slot 4 is reconized as card 1. I am not sure if thats normal or just a bug in the software. When I had my 780ti's in they always read x16 on both slots. I just can't wrap my head around this. I know there is no real performance gains from x8 to x16, but I bought the 5930k specifically because it had 40 PCI-E lanes. I would like to be able to use the lanes and hardware as stated in the product specifications. If anyone else can confirm this with a similar set up please do so. Any help or input would be appreciated!!! I can post any pictures or info needed.

Hello,
 
Are your PCI lane speed readings while the cards are under load? Have you tried manually setting the PCI gen speed of both 1 and 4 to Gen 3? Perhaps also try using the PCI mechanical shut off switches under the 24 pin connector to turn off all lanes besides 1 and 4.

That's a mighty clean looking inside.

ScourgeDL
That's a mighty clean looking inside.

Yes, super clean build. Caselabs is case with EVGA Classified Graphic card and Motherboard and EVGA Platinum 1KW.
Only now to install water blocks on graphics. I will buy Predator 360 90% because GPU. For CPU only I could stay and on H100 until die but I want to play games below 60C with normal fan speed.
Perfect Classified Build. 

Quick question.. This is both cards, individually, correct?

Have you tried installing only 1 card in slot 4? Do not install anything in slot 1, just to see how it reacts.

Once you try that, try the other card.


*edit... * I think Nvidia's sli bridge is only 60mm long.. It looks like you are in slot 1 and 3.. Not one and 4.

Grab the 3 way bridge out of your motherboard box, and install the card in slot 4. The 3 way bridge supports 2 way sli. Drop your bottom gpu one more slot and see if you get x16 - x16.


*another edit* finally got the picture opened on my phone... It is an 80mm long bridge, so I retract the above edit.

Can you test it with 1 card in slot 4 ONLY. do not Ali them, do not install the card in slot 1. Does it still act the same?

Sorry, I missed that in the mix of all the extra stuff.. No need for the extra is the slot itself is running in x8, as the other tests are completely invalid anyway.  Keep it simple.
 
Write down anything you have changed in the bios and reset it with the CMOS reset.  You can save the profile, but once it is saved, reset it.  Do not reuse the profile.  Test everything at stock and see if it makes a difference.  

For some reason I couldn't attach this pic to the above post so I put it here.

gtxjackbauer
Raymond, run the benchmark on GPU-Z where the question mark is on the right side.  It should show you what your GPU runs when on load.  AFAIK, our GPU's scale down when not in use.

I have put them under load on every benchmark I have access to and it never goes above x8 on card 2 in slot 4. I have tried the GPU-Z stress test it just stays at x8 3.0. I would agree that it just stays at x8 until put under load, but I have never seen it go to x16 regardless of the benchmark or game I run even at 4k. I also understand that there is probably little or no performance gain between x8 and x16. I have benchmarked them in numerous configurations and all the benchmarks come back with in margin of error less than 1% of each other. It is my enthusiast curiosity that makes me want to understand why? Is it the GPU? Is it the motherboard? Is it just the 980ti Classified? Are other brands and cards doing the same thing? Why can't I force x16/x16 in the bios? I just want the technical reason it does not go to x16/x16? I am happy with my build and I am not complaining the performance is good. I am just curious !

I think graphic cards are right, probably something with motherboard BIOS is not right at this moment.

Sounds like a motherboard/bios/cpu issue.

Since both cards work @ x16 in slot #1 that tells me it's not the cards.

enkrypt3d
I had this same exact issue (and still do) and been going back and fourth with EVGA support with no resolution... really frustrating. I Know that 8x vs 16x 3.0 PCI-E performance is negligable but it just bugs me when the board should support it...
 
btw there is no way to hard set the slot speeds beyond setting it to gen1, 2 or 3... which doesn't seem to do anything either.
 
Also I have 2 x EVGA 980Ti's with the exact same problem. Doesn't matter what slot I use it will not run at 16x/16x......
 
Same exact specs as you except I have the 5960X CPU and a 1300W PSU... same mbd, same bios version, same graphics cards, same everything..

Thank you for posting ! At least now I know it's not just my computer. EVGA tech support was very good and extremely nice considering I spent a few hours on the phone with them. Problem was they seemed just as confused as me when trying to figure this out. The real question now is it the motherboard or the graphics card ? I hope somebody from EVGA comments or they release a fix in a bios or driver update. Really is disappointing that it says it supports x16/x16 but it really doesn't.... Especially after dropping $1500 on EVGA GPU's and putting them in your $500 EVGA motherboard.

It's depressing. Stuff which worked perfectly on X58/X79/Z87/Z97 and other less popular chipsets doesn't always/at all work with X99. There is something in that silicon that seems impossible to nail to the wall and fix it permanently. Every board, from every vendor have some issues. Most are shared across the platform. Pretty much everything is crapping out to some extent with X99. Except simple builds CPU+vga+hdd/ssd, everything else is doomed to run into some funky issues. Meh...

ypsylon
It's depressing. Stuff which worked perfectly on X58/X79/Z87/Z97 and other less popular chipsets doesn't always/at all work with X99. There is something in that silicon that seems impossible to nail to the wall and fix it permanently. Every board, from every vendor have some issues. Most are shared across the platform. Pretty much everything is crapping out to some extent with X99. Except simple builds CPU+vga+hdd/ssd, everything else is doomed to run into some funky issues. Meh...

My x99 setup has been working just fine without any issues.