SLI bottlenecked by lanes?

[sb4ssman]

I recently upgrade from a 980ti, to a pair of gtx 1080s in SLI on an Asus z170 pro gaming with a 6700k. Everything is running great except Fallout 4 and I've been trouble shooting for days including uninstalling and reinstalling the game and wiping every setting from ini. For reference I've been getting weird artifacts in the game and it eventually crashes, but otherwise it looks like both cards are getting utilized and functioning great, except for the artifacts. 

 

No other game has any issues (Skyrim SE, Doom, H1Z1, and more).  In researching PCIe lanes, my 6700k has 16, and that is currently split between the 1080s at 8x each. I also have a samsung 950 pro on the M.2 slot. I have a wireless AC card on a 1x PCIe lane also... could that one lane be enough to prevent the 1080s from doing their thing?

 

I can test this out a little later when I get home but does anyone have any clever ideas about this or any work arounds? Many thanks.

[Jacktastic-Mofo]

3 minutes ago, sb4ssman said:

I recently upgrade from a 980ti, to a pair of gtx 1080s in SLI on an Asus z170 pro gaming with a 6700k. Everything is running great except Fallout 4 and I've been trouble shooting for days including uninstalling and reinstalling the game and wiping every setting from ini. For reference I've been getting weird artifacts in the game and it eventually crashes, but otherwise it looks like both cards are getting utilized and functioning great, except for the artifacts. 

 

No other game has any issues (Skyrim SE, Doom, H1Z1, and more).  In researching PCIe lanes, my 6700k has 16, and that is currently split between the 1080s at 8x each. I also have a samsung 950 pro on the M.2 slot. I have a wireless AC card on a 1x PCIe lane also... could that one lane be enough to prevent the 1080s from doing their thing?

 

I can test this out a little later when I get home but does anyone have any clever ideas about this or any work arounds? Many thanks.

As far as I know Fallout 4 has shitty SLI scaling, when I tried running it on my dual 960's it ran as well as a single 960 + 10%. Not a huge improvement.

[Hunter7263]

Some games simple arent happy with SLI. Some games see no performance boost at all and infact things like stuttering get introduced. Did you research if Fallout was one of those games.

[manikyath]

SLI isnt magic, even for the games that *do* support it, there's a notable portion of them that are absolutely terrible.

[zMeul]

artifacting could mean defect

doesn't mean it's OK if you "don't see" them artifacts in other games

[ARikozuM]

12 minutes ago, sb4ssman said:

I recently upgrade from a 980ti, to a pair of gtx 1080s in SLI on an Asus z170 pro gaming with a 6700k. Everything is running great except Fallout 4 and I've been trouble shooting for days including uninstalling and reinstalling the game and wiping every setting from ini. For reference I've been getting weird artifacts in the game and it eventually crashes, but otherwise it looks like both cards are getting utilized and functioning great, except for the artifacts. 

Just disable SLI for the games that do terribly with it.

12 minutes ago, sb4ssman said:

No other game has any issues (Skyrim SE, Doom, H1Z1, and more).  In researching PCIe lanes, my 6700k has 16, and that is currently split between the 1080s at 8x each. I also have a samsung 950 pro on the M.2 slot. I have a wireless AC card on a 1x PCIe lane also... could that one lane be enough to prevent the 1080s from doing their thing?

Not a chance. The 950 PRO and 802.11AC gets pushed to the DMI lanes.

[Hunter7263]

23 minutes ago, ARikozuM said:

 

Not a chance. The 950 PRO and 802.11AC gets pushed to the DMI lanes.

I was going to say that it isnt entirely true if the 802.11AC is in a pcie slot. It would depend on the motherboard and how its layed out. Some of them push the pcie x1 through the DMI and use an actual pcie lane. 

 

However since nvidia doesnt allow less than 8x for each card other wise they just wont work it isnt the case in this particular case.