GTX680 WC questions

Pantlegz

Diamond Member
Jun 6, 2007
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So, I've got a pair of GTX680's and I was thinking about getting myself a graduation gift and watercooling them but I've got a few questions. First would be 1 loop or 2? I know something like http://www.aquatuning.us/product_in...computer-airplex-Revolution-420-360-G1-4.html would be able to cool both of them at stock speeds, but it would be around the top of it's thermal capacity. I could do 2 smaller 120.2/3 or 140.2/3 setups to give me some room to OC without worrying about the loop keeping up. My next though was to run a single res/pump and 2 rad's in parallel to help keep the costs from getting too stupid. I was wondering if there was a better way to set it up. I was thinking GPU1->res->pump->rad1->GPU1. Would this work assuming I have a pump that is able to move enough water and a large enough res? Is there any simple guide that will give you an idea as to how large of a pump you might need to ensure adequate water flow without going overboard?
 

WoodButcher

Platinum Member
Mar 10, 2001
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One pump, one res, 2 full cover blocks, 1 or 2 rads in series not parallel you'll be fine with one good pump. You'll need to do the math for the rad sizes but if your goal is quiet, more is better.
 

Grooveriding

Diamond Member
Dec 25, 2008
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360+240 rad is enough for 2 680s and a CPU. You could even add a third 680 if you wanted to and it would be fine.

A single 360 rad could cool 2 680s. You could do res-pump-2x680 in parallel-rad-res.
 

Pantlegz

Diamond Member
Jun 6, 2007
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what are the pro's/con's of series and parallel rad setups?

I was thinking parallel and after the res so they'd have warm water pumped into them, cool it off and then each card would get cooler water and dump it back in the res.

Going with a series, or a single loop with 1 rad, the second GPU wouldn't be getting cooled as well as the first GPU because the water would already be heated up, at least some, by the first GPU.
 

Subyman

Moderator <br> VC&G Forum
Mar 18, 2005
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Most people are limited by what their case can fit, so that would be my first consideration. A RX360 could be all you need with the option to add another 240 in the future if that isn't adequate.
 

Pantlegz

Diamond Member
Jun 6, 2007
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My case isn't really an issue. I'm going to get something external made to hold the rad's at least, when I start designing it I may add room for the res(s)/pump(s) too, I'll see how much room I need and how I like the way it ends up. I'll update the thread when I have a rough draft CAD drawing of what I'm thinking...
 

Grooveriding

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Dec 25, 2008
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Ultimately, from what I've read - some may know more, the order of your loop is not going to play too big a role as the water temp will equalize throughout your loop.

In my system I did choose to go with warm water coming off components to a rad to cool them. My 680s go into a 360 rad to be cooled and the water comes out of that rad over my cpu, then to my vrms and then my NB, after that into a res to pump into a 240 rad and out to the 680s again.

If you're going to WC your 680s, I would highly suggest doing your CPU as well if you are not already. Might as well get everything under water for the benefits it brings and do it at once rather than adjust everything to account for adding the CPU down the road. One thing I've learned with water is it's a time-consuming pita to drain and refill a lot if you wind up doing trial/error on it. Should be much easier for you having the bulk of the setup outside of the case though, especially for bleeding. I have everything in my case and it is a PITA to bleed.

I have a 360+240 doing 2 680s, CPU and motherboard VRM+NB. 680s are about 40C under load and my CPU in a gaming load is mid 40s and high 50s/low 60s under linx.

I don't know enough about the differences between parallel/serial rads to give any input :)
 

OVerLoRDI

Diamond Member
Jan 22, 2006
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I'd feel confident with two GTX 680s and one 3x120mm rad. Adding a CPU to the loop as well? mmm not so much.

However I see you are going external, in which really frees up your radiator options.

I believe Grooveriding was talking about the GPUs being connected in parallel, not the radiators.
 

WoodButcher

Platinum Member
Mar 10, 2001
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what are the pro's/con's of series and parallel rad setups?

I was thinking parallel and after the res so they'd have warm water pumped into them, cool it off and then each card would get cooler water and dump it back in the res.

Going with a series, or a single loop with 1 rad, the second GPU wouldn't be getting cooled as well as the first GPU because the water would already be heated up, at least some, by the first GPU.


parallel vs series,
All cards are not created equal,,, meaning that two cards on air, same manufacturer, same fans, same builder and application methods, one card will always run hotter.
To run parallel on a single pump both sides must be even or balanced in the plumbing department which is almost impossible to achieve. One side will always be a little weaker flow that will over time accumulate the sediments and become weaker still causing your temps to vary that much more. Two pumps running parallel would alieviate this issue a bit but still you would have two different temps because now you two cards and pumps and sets of plumbing,,,,
Did you did mention something about cost in one of your posts somewhere? Empty your piggie bank and get out your credit cards, this ain't gonna be cheap.
Did I mention balanced plumbing? All tubing lengths on both sides must be equal, all bends in the tubing must be equal radius, when you install a wye you need to use straight pipe to balance the flow otherwise it will favor the outside of a radius, complicated stuff to do in a case you want to build neat or clean and you have limited space.
In a series loop the imbalance can work in your favor. Test the cards on air first, you'll find one card hotter or one slot, maybe from voltage or airflow in the case, any number of possibilities, but find out first on air then run your loop accordingly. As Grooveriding mentioned loop order is not that critical as you may think. The water temp from any given point in the loop does not vary a measurable amount, it is simply moving too fast but like him I too have always tried to build my loops in an order that satisfied my mind as "proper". Pump to the rad and then to the blocks to provide the coolest water possible. right, wrong or indifferent, that's what makes me happy.

Get enough rad to cool your loop w/o excessive fan noise and you will have built a good loop, other than that there is nothing to it!
 

OVerLoRDI

Diamond Member
Jan 22, 2006
5,490
4
81
parallel vs series,
All cards are not created equal,,, meaning that two cards on air, same manufacturer, same fans, same builder and application methods, one card will always run hotter.
To run parallel on a single pump both sides must be even or balanced in the plumbing department which is almost impossible to achieve. One side will always be a little weaker flow that will over time accumulate the sediments and become weaker still causing your temps to vary that much more. Two pumps running parallel would alieviate this issue a bit but still you would have two different temps because now you two cards and pumps and sets of plumbing,,,,
Did you did mention something about cost in one of your posts somewhere? Empty your piggie bank and get out your credit cards, this ain't gonna be cheap.
Did I mention balanced plumbing? All tubing lengths on both sides must be equal, all bends in the tubing must be equal radius, when you install a wye you need to use straight pipe to balance the flow otherwise it will favor the outside of a radius, complicated stuff to do in a case you want to build neat or clean and you have limited space.
In a series loop the imbalance can work in your favor. Test the cards on air first, you'll find one card hotter or one slot, maybe from voltage or airflow in the case, any number of possibilities, but find out first on air then run your loop accordingly. As Grooveriding mentioned loop order is not that critical as you may think. The water temp from any given point in the loop does not vary a measurable amount, it is simply moving too fast but like him I too have always tried to build my loops in an order that satisfied my mind as "proper". Pump to the rad and then to the blocks to provide the coolest water possible. right, wrong or indifferent, that's what makes me happy.

Get enough rad to cool your loop w/o excessive fan noise and you will have built a good loop, other than that there is nothing to it!

Holy crap man. Are you talking equal tube lengths everywhere? or just between the cards?

His cards are near enough to identical. Same GPUs, same blocks.

I feel like you are blowing a lot of little things way out or proportion.
 

WoodButcher

Platinum Member
Mar 10, 2001
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Equal in shape and size between the wyes, LOL,
If one side of the parallel flows even just a little better over time the difference would become greater as the loop became dirty. It would be more evident in a big loop with a lesser flow.
If a person is thinking parallel to get duplicate temps in both cards there are too many variables to make the effort worth while. The loop is only one of many variables, when in fact running series will get you comparable temps, well within the limits of the cards and a much neater case.
 

Elganja

Platinum Member
May 21, 2007
2,143
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81
single loop for sure (i have tried both ways)

i use a 360+240 for my 990x, chipset, mem, and 3 680's ... it's more then enough to cover them.

This is the order I run my loop:
Single Loop (serial): res/pumps -> gtx 360 -> GPUs -> gtx 240 -> cpu -> memory -> chipset -> repeat



I have a list of all my parts I used in my sig (click on the google doc, then look at the 2nd tab for a list of all my watercooling parts) ... it should get you started