SLI woes

[RimanDk]

Hey guys,

I just put together a new system: Gigabyte z97x gaming 5, i7 4790k, 2x Gigabyte gtx 970 g1 in sli, windows 8.1 pro x64, latest drivers.

It's not looking quite right. While the fps i am getying are definitely above my old 2600k + single gtx 680 setup, they are not quite as high as i expect them to be and the usage figures in afterburner are all wrong (i think). My 3d mark score i up in the 16000 region, which seems right, but while firestrike runs the gpu 1 shows usage between 50 and 60%, while gpu 2 stays rather flat at around 5% usage. On the other hand the power usage, memory usage. Heat and fan speed seem to go well hand in hand on both cards, which i find weird.

The obvious: I have installed my cards in the right pci-e x16 slots and they should be sharing x8 bandwidth. I have connected the cards with the sli bridge on the knob closest to the outputs. I have enabled sli for maximum performance in the driver and have left the physx option to auto-choose which processing unit to make use of.

In games the situation is much the same, with afterburner showing moderate usage on the first card and virtually none on the second. Games tested so far are Project CARS, Guild Wars 2 and War Thunder. I tried disabling sli in pCars and the difference was a meagre 10-15% in performance.

Am i missing something?

Edit: Forgot to mention I am running my system off a seasonic platinum 860W.

[Redut]

enable SLI, do it monthly

[Liquid]

Try switching the cards around see if it makes a difference

 

Also switch the Power cables around for the cards  the 6 & 8 pin to the other card and vice versa

 

Do you have another SLI bridge you can test try another one to see if it makes a difference 

 

The PSU seems suffice in power 

 

Also PCI-e 3.0 X8 should be enough for a 970 

 

http://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/3.html

[RimanDk]

I tested both cards individually in the top slot and both perform the same. 

 

Switched them around, same performance and usage graphs as in the OP.

 

Switched power cables, no change.

 

Flipped the SLI bridge, no change.

 

I have another SLI bridge lying around somewhere.. need to find it and try it, though I have doubts that will change anything. I will try to locate it, though =)