W/C for 4 x 295GTX

[RZA]

I have about an inch of space under the door, so this won't be a problem.

Ugh. This is going to be a challenge... 12 straight hours of research, and I'm not even close to a clear vision of how to make this happen.

Will keep updating this thread with more questions, details on choices made, and (hopefully) the build process.

 

[Flurp]

Flurp, the idea is interesting, but in Swarm's thread people suggest it doesn't typically work out well, unless perfectly executed. This will be my first WC, so perfect execution is unlikely to happen

Well you won't have a problem so long as:
1.) you have the same length's of tubing from the split to each block
2.) each card has the same block
3.) you have the same length's of tubing from the card to where they join back

So I think it is something you should look into, at the same time I do not recommend putting rads or multiple different blocks in a parallel loop.

here is a crude example of what I am saying you should do though

Click Me

 

[RZA]

Yeah, I got the idea. Will research more to see which of the two setups is the way to go.

 

[Flurp]

By the way, the reason most parallel setups don't work is because naturally the water will take the route of least resistance, so if you have a tube split in 2, 1 with a very restrictive loop and the other with a free flow loop, the one with the restrictive loop is not going to get as much flow as the other and therefore won't work as needed, that being said if all 4 loops have the same resistance/flow then the water is going to go in them equally, so while parallel loops are NOT for every circumstance there are plenty of circumstances where they can help alot, especially with the blocks you picked out

 

[RZA]

Okay, okay, I got the idea

From what I read so far, I think I'm pretty settled on the idea of having a 2-component system - case and rad(s) separate. This is cheaper and gives me more flexibility on "what goes where". Now, here's a question: is the placement of pumps important? That is, which of the two options is better, or are they equal?

1) Pump - GPU - CPU - pump - 10ft tubing - rad - 10ft tubing -back to pump
2) Pump - rad - pump - 10ft tubing - GPU - CPU - 10ft tubing - back to pump

In other words, does it matter whether pumps sit with rads or with case? I am thinking of keeping them with rads (so that the case, which is in bedroom, is even quieter), but not sure if it is a good idea. The reason I'm asking this now is cause that would influence the choice of a case.

One more: I read in some of the manuals that all the components of the WC system should be more or less on same level. Well the window I mentioned is about 4ft from floor - how does it impact my setup? Should I just get slightly more powerful pumps, or is it a no-go?

Thanks a lot for all your input BTW. I'm trying to educate myself through a lot of reading, but I totally realize that my knowledge is patchy and I might be asking stupid things.

 

[Flurp]

maybe It's just me but that water isn't gonna be the coolest when it hits the cpu... :\

 

[jmdixon85]

^Very true, 4 GPU's will be putting a lot of heat into the water before it gets to the CPU. I would rather have it CPU->GPU. The heat from the CPU won't heat the water up half as much as the GPU's will.

 

[jmdixon85]

Good question about that 4ft incline to the window. I'm thinking this:

Pump - CPU - GPU's - Tubing accross floor till window - Pump - 4ft Tubing upto raidiator - Back to pump.

Not sure how much difference this would make? Just seems logical to have the pump just before that 4ft incline.

 

[Ben333]

Just to clarify again, saying "by the time water gets to the (part) it will be too hot" is incorrect, the water is moving fast enough in a WC loop so that any one spot won't have a temperature difference of more than 1C from another spot. RZA, MCP 655s are damn quiet, you won't notice them if they're in your case. I always put my pump and res at the bottom of my loop to ease filling the system. This is pretty crude... but my WC method, heh...
http://ben.lostgeek.net/ben/~BasementWC/111_0624.JPG

Theres my s775 rig (I don't upgrade much) in my basement/work room. I can run that setup fanless when I want to with an overclocked Pentium D 820, and have ran an E7200 on that setup fanless at 4 GHz - high temps but fanless. While that doesn't look great right now, it has my main ideas for an easy WC - the pump and res are low, the res is large and easy to fill and the tubing is a bit longer for easy access to the motherboard. Also, as I said in post #12, you could build a nice box to keep the radiator(s) in your window, something that blows air out the window beside the radiator, then a box around the fans and radiator so it draws in outside air through the rad and blows it back out without cooling your room. For the pump, I'd recommend an Eheim, Iwaki or the pair of MCP 655s. I think now some mspaint drawings will be required to think about the placement of things, heh.

 

[Flurp]

Also while Ben333 is correct about the temp should equal out after the system is running for a small amount of time, it should be noted that this is only the case with a high flow rate loop... a restrictive loop will be different

 

[Ben333]

It has been tested. With two good pumps, he will still have good flow. His cards might not read out to the exact same temperature as each other but I doubt the 4th will be the hottest.

 

[Daddyjaxx]

The water is moving so fast through the blocks, it doesn't heat up very much at all.

 

[dark bishop]

Radiator
GPU block
sli fittings
pump

my recommendation as far as gpu loop goes.

 

[RZA]

Wow, that rad looks good - might be better than the monsta I was going to go for.

Is there a good roundup of 295gtx GPU blocks somewhere? Google produces individual reviews which are kinda hard to compare.

OK, I'm trying to think ahead, and here's the question: how do I know which part of the system is the bottleneck in terms of cooling performance? That is, how do I decide whether I need to build in an extra pump or an extra rad? Should I build in some kind of flow monitoring device from the very start?

And one more important thing: I see that those Danger Den blocks are sold with single slot PCI bracket. Does that mean that I will be able to install these babies right next to each other without skipping a slot? If yes, maybe I can cram 7 of these into that ASUS mobo? I know this is insanity, but hell, that's the whole point of this exercise.

 

[RZA]

Here's what I got so far:



Does it look good? This is based on the assumption above that I can fit 7 graphics cards into that mobo, and it is going to work. If this is not true, I will of course remove 3 water blocks.

Now, question about the case. As far as I see now, my requirements to the case are pretty modest:

1) SSI CEB compliant;
2) Holds 2 PSUs (with 7 cards there is no way I can get away with just one);
3) Has enough space for 2 pumps;
4) Doesn't have a lot of holes (I don't need ventilation anyway, so I'd rather have it quiet).

With this set of inputs, I think I can get away with something fairly cheap, say $150. Buying something more pricey won't get me anything. Or am I missing something?

 

[Spawn-Inc]

i know this (<click) isn't the block you need, but look at how they do a parallel setup. that's what you need to do but you can use those DD sli fittings.

that will ensure you have proper flow AND have less tubing then the bits power block you looked at. which btw i think was for the dual pcb version.

which one are you getting btw? single or double pcb?

Here's what I got so far:



Does it look good? This is based on the assumption above that I can fit 7 graphics cards into that mobo, and it is going to work. If this is not true, I will of course remove 3 water blocks.

Now, question about the case. As far as I see now, my requirements to the case are pretty modest:

1) SSI CEB compliant;
2) Holds 2 PSUs (with 7 cards there is no way I can get away with just one);
3) Has enough space for 2 pumps;
4) Doesn't have a lot of holes (I don't need ventilation anyway, so I'd rather have it quiet).

With this set of inputs, I think I can get away with something fairly cheap, say $150. Buying something more pricey won't get me anything. Or am I missing something?

fixed your link, so your going with 7 GTX295's now????

instead of that rad, i would go with this one. Nova 1080
the reason being the nova uses flat tubes instead of round tubes. it will provide better heat transfer and thus outperform the other one.

i would also get a different cpu block, heatkiller or Swiftech GTZ or XT.

 

[Conumdrum]

Aha, yes, your seeing the adding of a CPU to the GPU loop isn't that much. Here is the issue. The water temps difference btween the ambient air temps is called the Delta T temps. Just a term we use. The GPU's don't need a good DT, they don't need to be cooled as well, they are happy with running at 70C or even 80C. This means you need less rad to cool the GPUs.

On the other hand, pumping the high DT water to the CPU will keep your CPU uncomfortably hot, especially if you overclock the CPU. The CPU needs a LOW DT to perform well. Unless your ALWAYS in chilly air temps.

Your in SF? I'm sure you have 80F days in the summer. This is something you have to plan for. The ambient temps in the summer.

Having a single loop means you'll need more raddage than having the CPU and GPU seperate.

Look at this chart. Scroll down to Thermal Testing. Follow the orange fan line, high speed Ultra Kaze at 2000 RPM. 800 watts of cooling at a 9C DT. Add a i7 at 200 watts under folding load, take the line to 1000 watts, your CPU will probably be close to thermal shutdown.

Thats why you should have two loops. Of course a Feser Monsta would do better somewhat, not sure how much.

 

[Conumdrum]

That CPU block you chose is very old and isn't going to help CPU temps. It's a very old design, made back in the ealry Quad core days, for under 100 watt CPU's. DD has a TDX out now, but it's also surpassed by more than a dozen blocks now.

 

[Daddyjaxx]

You've upped it to 7 295's? That's 1500w right there. Am I the only one that thinks that 1500w is a tad much for one rad add the CPU and you're easily over 1700w. Even at 9x120, that's each 120mm cooling 200w. I suppose it's possible if that rad is good.

60 feet of tubing? WTH? Those two pumps aren't going to push 60 feet. They might push 60 at .25 gallon per minute.

I'm waiting to see this setup. 5 grand in CPU's and watercooling for them. Can you through a 275 for me? That's peanuts.

 

[RZA]

Hehe Well I do realize all this is easier talked about than done, and sounds like a pipe dream. This exercise is not only planning, but also feasibility study - at some point I may have to scale back or call it altogether. But I am fairly serious about this idea - I'm not just BSing and wasting your time. I do want to make it happen.

Conumdrum, point about two loops well taken. I'm pushing hard to minimize the number of boxes - if possible, I'd rather have one huge rad than two smaller ones. But you might be right, especially with 7 graphics cards the CPU might get fried.

How about I get 2 massive rads (say 2 NOVAs), and make one loop for 5 GPUs, other loop for 2 GPUs and CPU? This second loop should be fairly piece of cake for such a rad?

As to the CPU block, thanks for the tips - I didn't research that at all, just picked something at the same website to have a sense of total cost. Will look into what is real good before actually buying.

Finally, you say "look at this chart" but I don't see anything - there might be a broken link or something.

Daddyjaxx, 2 things. First, I don't expect to use up all that tubing - added some extra, in case I mess up, or cut too short and need to replace, or whatever. Secondly, someone else in this thread (Spawn I believe) said that tubing length doesn't matter too much. If it does - can I just get more powerful pumps, or this is something completely impossible?

My closet window is about 20-25ft apart from the spot where I was thinking to place the case. However, if this is a major complication, I might put the case itself into the closet as well (distance will reduce to like 5ft) and use cable extenders for monitor/keyboard/mouse.

As to "upped to 7" - I'm toying with this idea, but I can't really understand whether this will actually work. 2 things that bother me are the physical density of installation (will I be able to stuff all that in and connect the tubing etc?) and motherboard/OS limits (will it end up choking on 14 GPUs?)