Monday, December 1, 2014

Is SLI really worth it? Gaming experience with two GTX 970 cards in SLI


In the previous post, I described my experience with MSI GTX 970 Gaming cards running in SLI in the confines of the tiny Silverstone SG09 case. I only talked about the temperatures of the cards in that post and I have concluded that it is a bad idea to get non-reference cards in that case. This might be applicable to all Micro-ATX setups unless the case has expansion slots and the motherboard has the 2nd PCI-E x16 slot right at the bottom, giving the cards at least one free PCI-E slot in between them.

Now, let's forget about that horrible experience for a moment. What about SLI as a function? Is it any better than Crossfire, which I had a horrible experience with about 3 years ago.

I could test 4 games in the short time with SLI.

  • Crysis 3 (multiplayer)
  • Alien Isolation
  • FarCry 4
  • Call of Duty: Advanced Warfare.

The former two worked reasonably well. There weren't any observed micro-stuttering, although in Crysis there were couple of pauses which I had not observed so far with a single GPU, and both occasions I got killed.

But the latter two (FarCry and Call of Duty) would not work properly.

In FarCry, there were massive stuttering and negative scaling. The frame-rate would fluctuate rapidly so much as it would sometimes drop to a single digit. With a single GPU at the same graphics details, the frame-rate would hardly fall below 35fps. It was literally unplayable. 

In Call of Duty, there were issues such as flashing textures and the player's character unwilling to move forward. It could be jumped and moved to the side with some effort, but could not move forward. The issues disappeared soon after disabling SLI. 

There are of course work around for drivers issues. Using tools such as NVidia Inspector, suitable SLI profiles can be specified until the official support is received. There wasn't enough time for me to test it.

It is a widely accepted fact that both NVidia and AMD would first try to iron out the issues on single card setups before focusing on multi-GPU setups. As a result, day-one SLI support for new games is nothing less of a miracle. But I at least expected the default profiles would work reasonably well, perhaps with a scaling of about 50%. I didn't expect it to have issues such as seen in Call of Duty AW and FarCry 4 as it is the popular belief that NVIDIA drivers are superior to AMD's.

There are other feature restrictions as well. For example MFAA support that NVidia introduced with Maxwell (but not limited to Maxwell) was enabled with the 344.75 drivers but it would not function in SLI. I do not like AA because it comes with a massive performance hit, therefore doesn't concern me, but I'm sure there are people who buy a second video card just to enable AA in games and it is unfortunate that they cannot unleash the power of the second card for what they intended.

To conclude, I'm sure you can already sense where I'm going with this. Multi-GPU gaming cannot be recommended regardless of the manufacturer. From what I experienced, there is nothing special about NVidia cards – grass is not any more greener on the Green side. However it is possible that the issues could be attributed to the immature Maxwell drivers. Perhaps when it is time to upgrade again, SLI can be reconsidered as the drivers would be mature enough; but it is too soon.

This brings us to another discussion. Should I return the cards and get a GTX 980, which is the fastest single GPU card as of yet? Or should I stick with the GTX 970?

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