Posted by: jimhogan
Water Cooling (I lost control) - 07/08/2004 15:21
OK, so I woke up last Sunday AM and found an order confirmation on my screen. It looks like during a late-night lapse in judgement I inadverdently ordered a Tyan K8W S2875 and a pair of Opterons. Oh, well, water under the bridge. In for a penny, in for a pound.
Not only do I want to water cool this thing to reduce noise at my desk, but I would actually like to route the plumbing outdoors, to a deck next to my desk as that room is already warm. I am looking at using 2 Danger Den TDX water blocks with 1/2" tubing, but I don't have any sense of how much pump is needed to push coolant the 3 meters or so needed to get out to the deck. Any hydrodynamic experts out there or has anyone experimented with this?
A couple of other things I am thinking of:
One is to use a home-brew radiator and fan built with an automotive heater core and make my own reservoir. One other option was just to use a length of residential water heating baseboard (with some of the trim removed) and have the radiator be completely passive. Am I nuts?
I am thinking that during the winter I would want to have some sort of thermistor-controlled variable flow rate -- don't let water get so cold that it creates a condensation problem inside the room/PC. Am I nuts?
Can anyone offer comments on a 12V DC or 115V AC pump that would do the job and a speed control circuit (I am think 12V DC would be most feasible) that might work? Am I nuts?
There are lots of cooling forums out there, but I have looked at them and just don't find the commentary to be of the same quality and reliability as found here.
Posted by: TigerJimmy
Re: Water Cooling (I lost control) - 07/08/2004 16:55
Well, here's my $.02. I'm a mechanical engineer, but I'm not a thermal or hydraulic specialist, so others may have more appropriate comments.
Pumps are rated by pressure and flow rate. You don't need a very heavy duty pump, because you won't need a high flow rate, and you will not be lifting the water very far (maybe just a couple of feet, if that). The horizontal run of the coolant doesn't matter (within reason, with a really long run you start to factor in pressure losses due to the run), what matters is whether you are *lifting* the water -- that means pressure is required. You are just moving water in this application, with a relatively short run and without lifiting it much (if at all).
If you are going to roll your own, I would recommend the quietest fish tank pump you can find. Get a pump for a larger fish tank, as it will probably have lines that are easily adapted to the size you will be using on your computer.
When you are dealing with cooling, the thing you want to do is dissipate *power*. Knowing how many watts your CPU(s) consumes (when overclocked) can give you an upper limit of how much heat you need to dissipate (to be conservative, assume that all the electrical power is turned into heat). Convert the watts into something you can use to size your radiator pipe, like BTU/hour.
What you want is a system that dissipates heat at at least the same rate (or faster) than the CPU generates it. In my humble opinion, since CPUs are generally just fine to +50C, there is no reason to use active cooling. If you can cool it to room temperature, that is plenty good enough. If you can keep the cooling block to room temperature, or even somewhat above, you're fine. This eliminates the need for active cooling and prevents any condensation/dew point issues.
You *will*, however, need to move coolant through the system fast enough to keep the cooling block cool. You will also need to cool the coolant, which is where the radiator business comes in.
You pretty much have 3 options for cooling the coolant: passive convection, active convection (using a fan), and some kind of refrigeration. Its really a question of surface area. Those 3 options are arranged in decreasing surface area requirement. Completely passive is just fine, doesn't require any additional power, and is silent, but it is going to require a lot more surface area than if you blow a fan over it, or if you use some kind of refrigerant.
So, for cheap, easy and silent, I would use a long length of tubing with fins on it (like the home heating radiator you suggested). To test things, stick your little CPU cooler on a bright, halogen light bulb (100W+) and measure the temperature of the coolant. You need enough radiator and fast enough flow rate to dissipate the heat.
So, that's my $.02. Cooling is a function of coolant flow rate and the size of the radiator. Of course, the heat transfer rate of the little thing you stick on the CPU is a factor, but I'm assuming this is a constant. From a practical point of view, it would be really easy to build a radiator that is "overkill" for the application. Then, the faster you pump the water, the closer to room temperature you'll be, limited only by the CPU cooler's ability to conduct heat away from the CPU.
FWIW,
Jim
Posted by: genixia
Re: Water Cooling (I lost control) - 08/08/2004 20:28
Does that room remain hot in winter? You might want to consider an inside radiator for the winter. This would prevent condensation issues, and also a potential pipe burst if you should turn the PC off and the radiator froze.
Another option to consider is radiating to another (cooler) room or basement.
Posted by: gbeer
Re: Water Cooling (I lost control) - 08/08/2004 20:59
Speaking of Basements. Isn't pressure head only a problem when, the loop is not closed, or there is a big bubble in some part of the system?
Posted by: gbeer
Re: Water Cooling (I lost control) - 08/08/2004 22:42
An X-10 dimmer? Just curious.
Posted by: mlord
Re: Water Cooling (I lost control) - 08/08/2004 22:47
Since it's a closed loop system, I think any lift that may be done will be cancelled out by a corresponding drop on the way back in -- net effort to lift is nil in such a system with no leaks.
Cheers
Posted by: TigerJimmy
Re: Water Cooling (I lost control) - 09/08/2004 17:41
I think you should just have the radiator inside. Then you don't have to worry about freezing or condensation, or anything else. Simpler. If you get the CPU to something close to room temperature, that should be plenty good enough.
Jim
Posted by: genixia
Re: Water Cooling (I lost control) - 09/08/2004 18:03
Another thought - what lighting do you use in that room? I'm guessing that the heat from a PC wont be more than that of 2 lightbulbs. Maybe halogen bulbs could help mitigate your heat problem to the point where radiating your PC there won't be an issue.
Posted by: jimhogan
Re: Water Cooling (I lost control) - 27/12/2004 19:07
Well,
It is not finished, but all of this talk of AMD CPUs got me to pull a couple pictures off my camera. I did go with a radiator out on my deck, currently running a water/isopropyl mix.
The pics are on the big side (kept them that way for a detail-interested friend)
Inside the Computer
Out on the Deck
I have a couple quarts of methanol and am going to flush and refill with H2O/methanol and add some fittings at that time. I found a stopcock to put on the drain, I am making an in-line temp sensor and am looking to somehow get one of
these.
Right now I am hard pressed to get either CPU over 35C with cpuburn, but I expect I will hook those radiator fans up before summer. The Eheim 1260 pump moves lots of water and is quiet (mounted it on double rubber dampers which I am going to improve further still....)
Just install FC3 x86_64 last week. All is fast and very quiet.
Posted by: mcomb
Re: Water Cooling (I lost control) - 27/12/2004 19:22
Wow, how much have you been able to overclock with that setup or are you just using it to eliminate noise?
Posted by: Dignan
Re: Water Cooling (I lost control) - 27/12/2004 20:03
I must congratulate you. I've always admired water cooled systems, but never had the courage to do it myself. Yours is extra impressive!
My friend tried going with a water cooling system with the very first machine he ever built. Not a great idea. Apparently the machine was very loud, which is not good considering it was water cooled. He used it for almost half an hour before the smoke started to appear
Posted by: ashmoore
Re: Water Cooling (I lost control) - 28/12/2004 16:45
Jim,
Could you let us know what parts you used for this?
I too have always wanted a home brewed water cooled system but have never ahd the confidence to try it.
Posted by: TigerJimmy
Re: Water Cooling (I lost control) - 28/12/2004 17:41
Nice Job!
How do you keep the disk drives quiet?
Jim
Posted by: ashmoore
Re: Water Cooling (I lost control) - 28/12/2004 19:24
Thanks Jim,
I am starting on my new PC project in january and I want it super quiet.
One new water cooled system coming right up, I just hope it looks as cool as yours