Watercooling loop advice please

Cenedd · 7 Jun 2007 at 15:30

Afternoon all. I'm setting up my first watercooled rig and I'm hoping you guys can give me some advice as I've no previous experience to compare things too and I'm rapidly losing my hair over this!

The rig I'm building is aimed at being as near to totally silent as possible - hence the passive rads and w/c psu.

Watercooled Enermax Liberty - w/c psu's seem to be only really sourceable from Germany. Search for "Wassergekühltes Netzteil" and you should start finding them.

Hoses - I've ordered the Alphacool 10/8mm since the blocks and rads I'm using are Alphacool and 10/8mm. Is the damn stuff supposed to be so stiff?! It came in coiled 1m lengths and doesn't seem to want to be in any other shape than the bend radius it's already in. I'm a bit scared that when I connect things with it, it will put stress on their mountings. For example, I need to connect the gfx card to the RAM and I'm concerned it will put strain on (if not break) the dimm socket. Is the tubing just crap?

My loop is planned to be: Pump, Rad , cpu, gfx, ram, psu, pump
Any problems with that?
The RAM has non-replaceable barbs for 1/4" hose whereas everything else has 10/8mm. I could put a 1/4" barb on the output of the gfx card and the input of the psu but I'm a bit concerned that the reduction in diameter halfway through the loop will reduce the efficiency of the whole loop. I was thinking instead of getting a fittings that have two 1/4" outputs so that I could run two 1/4" in parallel:

Code:

                          __RAM_
                         /      \
-RAD--CPU--(10/8)---GFX < (1/4") > PSU---(10/8)---Pump--
                         \__RAM_/

Does this seem sensible? (or even make any sense, the way I've explained it?!)

Thanks in advance for the advice and comments. The fittings for this lot are driving me nuts. The fittings for the rads for example look simple don't they? But oh no, each one of those connectors has a tiny bit of hose between it and it's a real sod to get them in and keep them in line.

Gareth

Full spec:
Pump: Eheim 600 Station II 12v
Rad: 8x external Alphacool Cora passive rads
Cpu: Intel E6600 SL9S8 (wanted the S7 because I think it's cooler but, luck of the draw)
Cpu block: Alphacool Nexxus 775 (full metal, not plexi top)
Gfx card: BFG 8800 GTX watercooled
RAM: OCZ Flex XLC 6400 CL3
Mobo: Gigabyte GA-P35-DS4

pegasus1 · 7 Jun 2007 at 15:41

Cut the hose to the required length and then put it in very hot water for a couple of minutes. Take it out and bend it to the required shape and let it cool. viola.
Make sure you have the Res immediately before the pump, otherwise you will struggle to purge the system of bubbles.
Ive never seen the need to WC my RAM.

Cenedd · 7 Jun 2007 at 16:03

Cheers Pegasus. I'll give that a try. I knew it would soften when hot but didn't think it would stay in that shape when it cooled.

I went with w/c on the RAM because I'm trying hard not to have any fans and the RAM tends to get quite hot in still air.

<edit>
The pump is submerged in the reservoir so I'm hoping that won't be a problem and will help reduce pump noise.
</edit>

Gareth

Cenedd · 7 Jun 2007 at 18:42

Have had a try with boiling water but although it helps a bit, the tubing still returns to the bent shape (coiled) it came in.

What are people's opinions on the change in diameter of the cooling loop please?

Gareth

MikeTimbers · 7 Jun 2007 at 21:18

You've got two lots of 1/4" which doesn't make 1/2" but isn't a million miles from 8mm. Your biggest problem is not the diameter change but the incredibly restrictive loop you're going to have when you only have a weeeny little pump. You're going to get very low water flowrates.

Cenedd · 8 Jun 2007 at 00:51

I'll admit that the pump I got was certainly a LOT smaller than I was expecting from the pics on the order pages but I had thought that 600 l/h wasn't all that weedy. Am I that wrong? My main aim is silence, I'm not really looking at overclocking anything on this rig.....or at least I don't require to. If I find I've got the headroom to and need to then I might as well but it isn't my main objective. If the worst comes to the worst, I can always replace the pump I guess.

Do you think though that going from 8mm to a pair of 1/4" in parallel and then back to 8mm is better than going from 8mm to two lengths of 1/1" in series?

Gareth

w3bbo · 8 Jun 2007 at 07:31

Head presssure (lifting height) is more important than flow rate(l/ph).

E.g a pump with a 4m lifting height with 400 l/ph is better than a pump with 1m lifting height and 600 lph.

MikeTimbers · 8 Jun 2007 at 22:52

If that 600lph is more than 150lph through that loop I'll be amazed!

Cenedd · 9 Jun 2007 at 18:56

Hmmm ok. I'd naively assumed that rate of flow was more important as from pump (lowest point) to top of rad (highest point) is far less than a meter.....not realising that lift height would imply how much loop 'resistance' it can cope with.
For the stuff I'm trying to cool, is 150l/h dangerously inadequate?

Nobody got an opinion on the diameter change?

Gareth

MikeTimbers · 9 Jun 2007 at 23:56

600lph is the free-flow best case flow rate. Imagine the pump is sitting in a bucket of water with nothing attached to the outlet. That's 600lph.

Now put 8 feet of tubing. That adds resistance and reduces the flow.

Now add a cpu block. That adds a lot of resistance and reduces flow.

etc.

Now consider your question about the step down in the diameter.

8mm ID tubing has a diameter of 8mm. call it a circumference of 25mm (8mm*Pi).
1/4" is 5.5mm so diameter of 5.5mm. call it a circumference of 17.25 (5.5mm*Pi). But there's two pipes so that's 34.5mm.

Where the water touches the wall (the circumference of the pipe) it is slowed down by the contact with the wall. So the single 1/4" pipe has a lower surface area to impede the flow in a single pipe than 8mm but the two pipes have a higher surface area and are more resistive.

PLUS, the 8mm is more than twice the "bore" (50.25 square mm vs 23.75 square mm) of the 1/4" so the larger ID allows more water through it than two 1/4" while having a lower surface area. This means the two 1/4" tubes will be more resistive than a single 8mm pipe going in serial.

Clear?

pegasus1 · 17 Jun 2007 at 08:28

MikeTimbers said:
Clear?

2 questions spring to mind Mike.

1 Will it make any difference if my pump is the highest thing in my loop or sits at the bottom of my case.
2 Will my MCP655 12V DC Pump be sufficiant to push the coolant around a loop consisting of the following
MCR220 Radiator
MCR120-QP-B Radiator
Swiftech MCW60 VGA Waterblock
Swiftech MCW30 Chipset Waterblock
Swiftech Apogee Extreme Performance Universal Waterblock
EK-Multioption RES 200 (230ml)
About 5 Feet of tubing

Im going to add the single Rad to my existing loop and move the pump from the floor of the case to sitting on top of the PSU (large Chieftech Dragon case).
Cheers

w3bbo · 17 Jun 2007 at 09:16

1. Having the pump highest will cause problems when initially setting up your loop as it won't prime without a constant feed of water - once you have primed and bled the system then having the pump higher than anything else wont hurt - just make sure all the bubbles are out of your loop before putting the pump high.

2. Yes.

WJA96 · 17 Jun 2007 at 11:10

8 cora's will not cool that lot. And you need a REALLY hefty pump with so many blocks.

I had a 12-cora system with 3 loops (6, 3, 3) and that barely cooled a P4, a pair of 7800GTX's and a couple of hard disks.

If you're serious about passive cooling then it's going to cost mega-bucks (believe me - I know

).

MikeTimbers · 17 Jun 2007 at 11:39

Will the pump push water around that loop? Yes. But don't put it at the top of the loop.
Will you get good flow-rates? What's good? The DDC would be better than the D5. See here. If you go DDC make certain it's the 18W version and get the Plexi top.

Are you really trying to go passive? If you are, you will need really big radiators outside the case preferably horizontal with nothing restricting convection above or below. And don't even think of over-clocking (i.e. over-volting) or planning on running 24/7.

pegasus1 · 17 Jun 2007 at 12:57

w3bbo said:
1. Having the pump highest will cause problems when initially setting up your loop as it won't prime without a constant feed of water - once you have primed and bled the system then having the pump higher than anything else wont hurt - just make sure all the bubbles are out of your loop before putting the pump high.

2. Yes.

Cheers mate.

Actually the pump wont be the highest thing in the loop, the twin rad is at the front below the grill but im puting the single rad at the rear and top above the PSU using the 120mm rear vent.
The Res runs externally and verticaly attached to the rear of the case about half way up. The single is directly after the pump (the Res before) so i can prime and bleed with the pump and single below the Res and then fix them back in place.

WJA96 · 17 Jun 2007 at 13:43

MikeTimbers said:
Will the pump push water around that loop? Yes. But don't put it at the top of the loop.

Can I ask why not? Surely, as long as it's below the level of the return what difference does it make?

MikeTimbers said:
Will you get good flow-rates? What's good? The DDC would be better than the D5. See here. If you go DDC make certain it's the 18W version and get the Plexi top.

If he's really talking about having one single array of Coras then he needs a REALLY oomphy pump as the Cora is simply a series of 420mm finned pipes with an internal diameter of 12mm and 4 right angled connectors (500mm/tube in total) so with an 8-tube array he's adding an extra 4m of piping to the system and unless he uses 1/2" connectors there will be a pressure differential at the start of the array.

I've build a couple of passive Cape Cora systems now and I would never mount more than 6 together on a single loop. If you must have 8 Coras then use a really hefty pump like a centrifugal one with a good head on it (Alphacool 150 will lift water 6m compared to the DDCs at about 2m at best) to overcome the back-pressure of all that piping.

MikeTimbers said:
Are you really trying to go passive? If you are, you will need really big radiators outside the case preferably horizontal with nothing restricting convection above or below. And don't even think of over-clocking (i.e. over-volting) or planning on running 24/7.

Again, can I ask why you are recommending horizontal mounting? The manufacturers specifically recommend vertical mounting so as to give the very best airflow through the fins (if you look at them you will see they are closed off, so horizontal mounting would trap the beside the tube and the cooling will be significantly worse). If you were referring to a large panel radiator like an airplex 1800 or an Alphacool Mo-Ra then please ignore this.

I had a 12 cora system (6 on each side of a Lian Li V600 case) with 3 loops and that just cooled a high thermal load performance system (overclocked P4, 2 7800GTXs and a few other odds and sods) so it is possible, but you need to keep pumping the water round at a decent rate and (possibly most important of all) you need a low atmospheric temperature for the heat to be lost into. It is possible, but ultimately I found that two or three Zalman Reserators worked best.