GeForce GTX 970 Strix OC sli vs 980 vs 780ti

[SirBerries]

So since it's coming up to Christmas I've decided I want to upgrade my PC. I have around £600 to spend but I can go over a bit. What's the best value of money? What gives the best performance? etc. One thing that is very important is the amount of noise it makes. My build is already quiet loud and I'd like for the cards not to be super loud but haven't found any reviews on the sound. I've done some research and I'm down to 4 cards:

Asus GeForce GTX 970 DirectCU II OC Strix (not sure what the difference is between the normal and the strix but people say it's better so some advice on that would be nice): http://www.overclockers.co.uk/showproduct.php?prodid=GX-352-AS

Asus GeForce GTX 980 DirectCU II OC Strix (again I'm not sure what the difference is between the evga one and the strix but people say it's better so some advice on that would be nice): Cardhttp://www.overclockers.co.uk/showproduct.php?prodid=GX-354-AS

EVGA GTX 980 SC: http://www.scan.co.uk/products/4gb-evga-gtx-980-superclocked-7010mhz-gddr5-gpu-1241mhz-boost-1342mhz-2048-cores-3x-dp-1x-dvi-i-1x-h

EVGA Nvidia GTX 780Ti SC: http://www.amazon.co.uk/EVGA-Nvidia-780Ti-384-bit-Graphics/dp/B00GJLUC8E/ref=sr_1_9?s=computers&ie=UTF8&qid=1415969939&sr=1-9&keywords=780ti

All of these I've done some research on and they seem to be the best value for money. If you could advice me what to get it would be great. Also I'm not sure which models, as I said I don't really know the difference between strix and not strix so if someone knows please tell me and any advice on what make to get would be awesome. I play games like csgo, bf4, arma 3 and soon to be AC Unity and Far Cry 4.

Thanks you for your help and time,
James (SirBerries)

 

[AshyCFC]

The strix cards by Asus are very quiet if Noise is a concern for you.

So here's how I see it:

the 780ti is better than the 970 but worse than the 980.

In my opinion I would go the single 980 because you can upgrade in the future where as with the SLI option you are then limited by what you can(you'd have to replace 2 cards instead of just adding one in future)

I'm not sure whether you play at but you can find benchmarks for ultra high resolutions 1440p and 4K in this review: http://www.hardwarecanucks.com/forum/hardware-canucks-reviews/67652-nvidia-gtx-970-sli-performance-review-5.html

The charts contain both the numbers for SLI 970/980 and single 980/970/780ti