How powerful of an AIO do you need to cool a GPU?

[Gerr]

I just got an EVGA 1080 FTW2 card.  First thing I did was to see how much of an OC I could dial in, so I set the Voltage to +100%, Power to 120%, and Temp to 92*.  Before I started to increase the Core or Memory settings, I wanted to see how high this got me.  Though Valley benchmark does well, I find that playing an hour of Witcher 3 is a better stress test and after doing that, I has a max temp of 78* with a boost that settled at 1987Mhz.  I don't like either of those numbers.  I was able to bump the core up by +10, but any higher and the temps got into the low 80's and I experienced crashes.  Looks like I didn't get a good GPU chip.  Thus I would like to liquid cool it to bring them temps down and hopefully, let me OC some.  I would really like to get into the low 2000's on my OC.

 

I plan on using the NZXT G12, but need an AIO to partner up with it.  I would prefer Corsair as my system already has a 100i v2 that is cooling my CPU, so having just one software to run both AIO's would be ideal.  I just don't know how powerful of an AIO I would need.  The G12 does say it supports the H55 and that would fit nicely, but is it powerful enough?  I would replace stock fans with Noctua fans, so just need recommendations based on the AIO's, not the included fans.

[TheRandomness]

Considering a thick 120mm radiator can cool 2 R9 290s, a single 120mm AiO should do fine.

[Coaxialgamer]

You can definitely get away with a 120mm aio. Even the 500w r9 295x2 gets away with it. Because of the larger die size of gpus, power density is super low, making them easier to cool. 

 

[PascalSignifica]

120mm should be enough but you should go for a semi custom solution like the Alphacool Eisbär and Eiswolf

[Damascus]

3 minutes ago, PascalSignifica said:

120mm should be enough but you should go for a semi custom solution like the Alphacool Eisbär and Eiswolf

At that price range it's better to get a hybrid kit.  Oh yeah @Gerr why not get one of evga's hybrid kits? The H55 has no software, nor does the hybrid cooler from evga but you need the vrm cooling provided by the hybrid kit.

[Gerr]

Would EVGA's hybrid kit work better than the G12 with an H55?

 

I am trying to minimize the amount of software I am running and since I am already running Corsair's Link to manager my H100i v2, thought another Corsair AIO would be best.  I even have a spare NZXT X41, but trying to save that for a later build.  I also have a H75 in a PC I was going to sell, so could swipe that and replace it with a good air cooler, but the amount I would lose on resale value added to the cost of the replacement cooler, I think I would come out in the negative, so was just going to buy an H55.

 

Other than the number of fans, anyone know if there is any difference between the H55 & H75?

[Damascus]

6 minutes ago, Gerr said:

Would EVGA's hybrid kit work better than the G12 with an H55?

Yes, especially for overclocking.   The Kraken g12 has no vrm cooling whereas the hybrid kit has excellent vrm cooling.  Try and push a crazy oc without vrm cooling and you may blow out a couple capaciters.

 

Also the H55 and hybrid kit have absolutely no software.