Adding GPU to loop, not enough cooling?

[felang]

Currently I´m running a loop consisting of a D5 pump EX240 + EX140 rads cooling a 2600K @4.5ghz and a single GTX 680. My case is a Corsair Carbide 500R so I am limited to a single set of fans (no space for push-pull) on the EX240. Currently I run the pump at level 3 of 5 and am using only a pair of Corsair quiet edition fans. These fans are definitely quiet (I have them configured at about 900rpm) but are not very effective. While gaming both my CPU and GPU stay below 55 deg, lower if the AC is on (about 21 deg ambient, normally about 27 deg).

Do you guys think I could add another GTX 680 for SLI into this same loop? Maybe upgrade the fans to some Corsair perfomance editions, and raise the pump to max flow. I´m not looking for crazy low temps, I´m happy if everything stays under 75 deg, 70 deg would be ideal so the GPU´s don´t throttle.

 

[T_Yamamoto]

I would add another rad if I were you.

 

[Bubbleawsome]

Me too, but I would try it first, then maybe add a x2 120mm rad for the 2nd 680 if it gets to hot. I'm not really into water cooling but I would set it like this. CPU> smaller rad> gtxs> bigger rad> CPU. I don't know where pumps go though.

 

[BrightCandle]

By EX series radiators I assume you mean the XSPC EX240 and EX140. In terms of cooling these are thin radiators, so somewhere around 90W per 120mm fan at 800rpm maintaining a delta temperature of 10C. So in all with low speed fans you can cool roughly 300W at your current fan speed.

Currently you have a 150 W overclocked CPU combined with a 180W GPU, so you are overloading your loop from the ideal by about 10%, the delta at full load is probably going to be somewhere around 11C, so that is OK.

Adding another GTX 680 without any additional cooling will put another 180W into the loop, now your total would be 510W of heat, which would put your delta more like 18C. That is too high for a CPU with that overclock, but its fine for the GPUs. You'll likely find the cooling once you add an additional 680 is worse than high end air cooling because of the high delta.

Adding faster fans isn't going to help much, the EX series is a high Fins Per Inch design which maximizes cooling for low fan speeds, its likely to respond poorly to additional fan speed past about 1200rpm.

 

[felang]

By EX series radiators I assume you mean the XSPC EX240 and EX140. In terms of cooling these are thin radiators, so somewhere around 90W per 120mm fan at 800rpm maintaining a delta temperature of 10C. So in all with low speed fans you can cool roughly 300W at your current fan speed.

Currently you have a 150 W overclocked CPU combined with a 180W GPU, so you are overloading your loop from the ideal by about 10%, the delta at full load is probably going to be somewhere around 11C, so that is OK.

Adding another GTX 680 without any additional cooling will put another 180W into the loop, now your total would be 510W of heat, which would put your delta more like 18C. That is too high for a CPU with that overclock, but its fine for the GPUs. You'll likely find the cooling once you add an additional 680 is worse than high end air cooling because of the high delta.

Adding faster fans isn't going to help much, the EX series is a high Fins Per Inch design which maximizes cooling for low fan speeds, its likely to respond poorly to additional fan speed past about 1200rpm.

Yep, XSPC EX series rads. In that case maybe I´ll just keep the reference heatsink on the second 680.

I wish I could add more/thicker rads to my case, just doesn´t seem possible unless I buy a new one. I wish I would of decided to WC before buying my current Carbide 500R.

Just to make sure I understood correctly, you´re saying that currently I should only have a T delta from ambient of 11 deg at full CPU + GPU load? I believe it´s worse than that currently.