I know you don't want to, but you should remove the center card and see if the temps improve and the lag spikes fade away.

Cramming three cards on air obstructs airflow to the top two cards.

What other games are you playing? CSGO runs really fast on a single card. You can disable SLI and the bottom cards will cool off when you are playing CSGO. That will not help airflow to the top card though.

Also, how are your fans set up and what case?

Scarlet-Tech
I know you don't want to, but you should remove the center card and see if the temps improve and the lag spikes fade away.

Cramming three cards on air obstructs airflow to the top two cards.

What other games are you playing? CSGO runs really fast on a single card. You can disable SLI and the bottom cards will cool off when you are playing CSGO. That will not help airflow to the top card though.

Also, how are your fans set up and what case?

Actually removing is not  a solution - i have one more card and was going to use it as 4-way SLI.
Will try to removing center card and let you know.
 
Im playing much different games like GTAV, Assetto Corsa, Crysis, etc.
Case: Corsair 900D.
Fans location:

try re-installing the drivers and evga precision.
had the same problem with heat on my old 780ti.
after re-instal everything was fine,must have been a corrupted driver or precision for mine.

If you have thermal paste that is non conductive, you could try refreshing your Tim. It only takes a few minutes.

On the back of the card, there are 4 screws with Springs around the core. Remove those 4 and the one at the corner of the I/O bracket. Gently remove the cooler and disconnect any lights and fans.

Use either rubbing alcohol or Articlean 2 part cleaner to remove all of the old thermal paste and clean the die.

Apply new thermal paste. You can use the dot method or spread the Tim. I personally prefer to spread the Tim as I have encountered less air bubbles.

Then, reconnect lighting and fan connectors, and reinstall the cooler. Tighten the 4 screws in a cross pattern then the one at the edge of the I/O bracket and test out the card.

Yes, those temps are fine. Honestly, the 75c you are getting with 2 cards is fine as well.

From your diagram of your fans, I was curious about the two pointing down as exhausts at the front of the hard drive cage. I would think that may disrupt the airflow coming in the front a little at least, which could possibly pull air away from flowing across the cards. Try just disconnecting those two fans to see if it allows the flow to push through better. If it does, turn them over and make them intakes to push more positive pressure into the upper compartment.

I don't know that it will help at all, but it is just an idea at this point.

nickbaldwin86
CSGo can run surround 4k on one 980... just saying. I am sure you didn't buy 3 just CSGo.
 
get a few high flow fans and point them directly at the cards... you should be fine.
 
Also manually adjust the fans on the cards to ramp up quicker. have them go to 100% fan @ 75c

You just said everything that has been said, lol :-p

You can set a max FPS in CSGO using the console. But otherwise I would focus more on finding a way to get more cool air into the case.

Scarlet-Tech
Yes, those temps are fine. Honestly, the 75c you are getting with 2 cards is fine as well.

From your diagram of your fans, I was curious about the two pointing down as exhausts at the front of the hard drive cage. I would think that may disrupt the airflow coming in the front a little at least, which could possibly pull air away from flowing across the cards. Try just disconnecting those two fans to see if it allows the flow to push through better. If it does, turn them over and make them intakes to push more positive pressure into the upper compartment.

I don't know that it will help at all, but it is just an idea at this point.

Ill make some experiment tommorow with fans.
So, if 75C on load (with 100% fan load) is ok - 3 cards at 81C on full load is ok too, right? Nothing to worry?
This is what i actually want to know.
(currently thinking about water cooling but it seems to be a bit complicated)
 

Scarlet-Tech
It isn't as complicated as it looks, it is just absolutely expensive as heck.

81c should be fine with three cards, but the more airflow you get, the better. If you are getting lag spikes, then you may be getting warmer on the top card causing he issues.

My current build ive just completed (and having problem ive described) is worth ~10k$.
So i dont think additional 1-2k to make it working perfectly is not a problem at all.
Thanks for answers and help. Ill play with fans tommorow and let you know if it will fix the problem.
Do you mind sharing some good water cooling builds to buy? One which will fit 4-way SLI perfectly (i have 4xGTX980, just installed 3 of them right now to make tests).
 

Scarlet-Tech
I have always been a fan of EK waterblocks, but many others like koolance, bitspower, alpha cool and multiple other manufacturers. It basically comes down to looks honestly.

If you go with ekwb.com, you can send them a support request email, and they are awesome enough to send you a full quote with everything you will need to set up an awesome system and be fully ready to function.

Perfect. Thanks again for help.