SAPPHIRE HD7970 Vapor-x 6GB crossfire vs SAPPHIRE R9 290x Vapor-x 8GB for 3 x 27inch Monitors

[Icykill]

I have a SAPPHIRE HD7970 Vapor-x 6GB with 3 x 27inch Monitors.
I use these for graphics work and also gaming on the highest settings.
In the games I play, I only pvp. I have a second SAPPHIRE HD7970 Vapor-x 6GB in another PC and I am considering wether to crossfire them or get a SAPPHIRE R9 290x Vapor-x 8GB and sell one of the SAPPHIRE HD7970 Vapor-x 6GB.
What will give me the biggest performance increase and future proof me for the next 18 months to 2 years.
I ask this because I have limited experience with Crossfire, I had been a Nvidia SLi user for 10 years before I got my SAPPHIRE HD7970 Vapor-x 6GB.
I am under the impression that Crossfire only gives you the maximum GDDR on the the master card and does not double the available memory

 

[Suztera]

It still the same thing with AMD crossfire. You run both card with the lowest clocks speed of the two cards and the lowest amount of vram (GDDR5). They do not double up. SLI is the same.

R9 290X is faster than a HD 7970.
HD 7970 crossfire is faster than a R9 290X.
R9 290X crossfire is faster than a HD 7970 crossfire.

You could crossfire depending on your motherboard. However, crossfire will require more power so you need to check if your power supply meets that requirement.

 

[Gam3r01]

Its actually quite similar to SLI.

As for the cards, 290X>7970, but 7970 Xfire is better than a 290x, its essentially a 7990.
Since you are considering 7970x2 or a 290x, pull the Xfire rig. That would give you the most performance, the only perks for the 290x is for the upgrade path.

 

[Icykill]

My system is more than capable to run crossfire with both motherboard and PSU

Thanks for the answers... Still not sure which way to go... I used to have some compatibility issues with SLi... One of the reasons I went for the single card with high vram
Does Crossfire have the same issues?
Also if I move to 4k monitors in the future, will the Hd7970 solution be capable?
If not, I'll go with the R9 290x and look at crossfire with them

 

[Suztera]

Crossfire have similar issues. But when it works, it works well.
By the time 4K monitors are mainstream, i would expect the newer gpu will be more capable of running 4k gaming. I would advise you to not think about 4k for now.
R9 290X with 3 monitors should be ok.

 

[sora]

I would definitely get the 290x. You could easily SLI.