Corsair Obsidian 800D water cooling build questions.

[Lenkas]

Hey

I know this has been asked a guzilion times but here I am asking it again.
All my previous rigs were air cooled and in 2010 I wanted to make my first water cooled PC but didn't have the cash so I dumped the project. A week ago I bought a used 800D, that is pretty much brand new and now I want to put water cooling in it.

I've done a bit of research about it and came up with a setup that I'd like to show below and ask a few questions about it.

My spec atm are:

CPU: I7-2600k
MOBO: GA-P67A-UD5-B3
RAM: 16GB Corsair Vengeance
GPU: Sapphire HD6950 2GB
SSD: OCZ Vertex 3 120GB
PSU: 850W Antec Quattro

The 2600k has been OCed but put to stock 'cause I preffered lower rpm and less noise.
With WC the 2600k will get a decent OC.
The 6950 has been successfully flashed to 6970.
I will be buying another 6950 so I will be running CFX 6950's flashed to 6970.
The Vengeance is cooled by Corsair Airflow.

The 2600k OC is about 150W?
The 6950 is about 250W (500W)
Mobo is ?? watts.

Lets say max 700W needs to be cooled.
360mm rad at medium fan speed dumps like 500-600W
120mm rad at medium fan speed dumps like 150-200W
140mm rad at medium fan speed dumps like 150-200W
Total: 800-1000W cooling power?

I'm leaning toward the single loop more than the dual loop.
Here is the picture of first version:

The loop goes:
Hottest water goes from 2nd gpu -> 140 rad -> res -> 360 rad -> 140 rad (at this point water would be coolest) -> mobo -> cpu -> 1st gpu -> 2nd gpu -> repeat...

I realized that hottest water from gpu going to 140mm rad on bottom, will dump the heat in air, so the warm air will go over the RAM's and through the 360mm so that is a no go.
After more research I realized that I can't fit a 140mm rad on the back, since the 140mm fan is snug so I switched to 120mm rad in the rear (still debating over push/pull slimmer rad or just pull and thicker rad).
And after some more thinking I noticed that the bottom 140mm setup won't work either. There is 130mm room but the rail that PSU sits on blocks it a little so 25+80+25 wont work. Switched that rad to 140mm 60mm thickness in push/pull.

So here is the new version:

The loop goes (i drew it here):
Hottest water from 2nd gpu ->360 rad (to dump the heat asap) -> res -> 140 bottom rad -> 120 rear rad -> NB/SB -> mosfets -> cpu -> gpu 1 -> gpu 2 -> 360 rad -> repeat...

It's a bit complicated but looks good.
There is a drain port at the back of the bottom 140 rad, and the fillport is at the res.

Parts list:

1x Sapphire HD6950

1x 360mm radiator (debating here over 80mm Monsta in pull configuration (i've read that pull is better than push) or a 64mm EK XTX in push/pull configuration) but I am leaning more towards EKWB since I'm from Slovenia and so are they and they are basicly across the street.

1x 120mm radiator EK XTX 64mm
1x 140mm radiator (one that has a drain port (the XTX 120mm has it but XTC 140mm doesnt ) so UT60 60mm)
1x CPU block (prolly EK (I have no idea about the diffrence in supreme ltx and supremacy))
1x MOBO block EK-FB Kit GA P67A-UD7 (compatible with my UD5).
2x GPU block full cover EK-FC6970 (compatible with my HD6950).
2x D5 pumps that fit koolance res pump combo (this depends if I need two pumps for my loop)
1x Koolance reservoir dual loop pump combo (this depends if I need two pumps for my loop)
1x Flow meter
1x Water temp meter with LCD's
1x Drain valve
1x 140mm fan

All the tubing I'd like blue transparent (1/2''?)
All the fittings I'd like compression ones, will need a few angled ones thinking of Bitspower.
Liquid, either I'll get EK-Ekoolant or Deionized water at work and add stuff like biocides to it.
The only thing I'm scared about is the corrosion of the nickel, brass, cooper and aluminium.
Kill coil (silver coil) and PT nuke (cu biocide) will be included.

Stuff that I have:
Corsair Airflow for RAM's
A bunch (8) of Xigmatek XLF-F1256 from EKWB.


I hope I covered everything and if I missed anything or something should be changed or is wrong please tell me.
Any additional info I get from you guys and girls would be very usefull.

 

[tinmann]

Why not go straight to the cpu from the 360mm rad then to motherboard and then into the rear 140mm, gpus, bottom mounted 140mm rad and back into reservoir.

 

[Lenkas]

Do you mean like this?:

Like I've said in my first post, I'm trying to avoid heat dump into the case.
In this case. "warm" water from mobo and cpu would be duped into the rear 120mm making it dump hot air into the case over the 360 exhaust
and the GPU's are the hottest so all the heat would be dumped into the bottom 140mm rad and that would make hot air go trough whole case, over ram's over 360.
Pretty much all the heat from mobo, cpu and gpu would be dumped into the case and over 360. While it does look cleaner than mine, its not as effective. It's like my first design.
My second design setup dumps most of the heat that comes from gpu's into the 360 and exhausts it.

I hope I made it clear

 

[rofl_my_waffle]

What you are saying does make sense if it were true.

The water travels very fast. At least fast enough to average the temperate of the loop across components. Max there is a 1C-2C difference between one component to the other. So no matter how you order your loop, its going to be blowing hot air. Its not like water will drop 10-15C after going through the radiator.

Also your wattage calculations are way off. The published TDP is never accurate, they quote max board power draw as a reference for buying a PSU. The actual power draw can be obtained through a watt meter at the plug (which is also skewed higher because most PSUs draw around 20% more power because they don't convert AC to DC at 100% efficiency). If you don't have a watt meter, look for power consumption reviews. From what I gather a 2x6970 with a 1st gen i7 already clocked at 4Ghz would use 450W, overclocking the cards would use around 550W. This is under stress tests, actual system power during gaming would be lower.


For the water cooling setup. The bay reservoirs with mounted pumps cause vibrations that can be loud and defeats the purpose of watercooling. I suggest you avoid that route.

Putting pumps in series doesn't actually do much not that you need that much pumping power anyway. Yes we are all brainwashed to think we need bigger things but we seriously don't need a bigger pump. I have aquarium pumps that can over perform ten D5 pumps put together, but what is the point? As long your water moves fast enough so that it doesn't rise by 2C between each component, it is good enough. But that is an incredibly low bar to clear so that's why you don't see larger pumps on the market. It is just going to be loud for no reason.

 

[Buzz247]

At least fast enough to average the temperate of the loop across components

True to the nature of the WC systems we use. Maintain flow, order becomes moot. However, you can increase time to reach system liquid temp equilibrium by not loading res with heated water. a couple C difference, so fairly negligible, but in spirit of full disclosure, deserves to be said

The bay reservoirs with mounted pumps cause vibrations that can be loud and defeats the purpose of watercooling

This is true - but if you properly mount it, and apply a 2mm layer of neoprene under it, it will be fine. Been there done that.

2x6970 with a 1st gen i7 already clocked at 4Ghz would use 450W, overclocking the cards would use around 550W

This is a more accurate assumption of TDW needs

Putting pumps in series doesn't actually do much not that you need that much pumping power anyway. Yes we are all brainwashed to think we need bigger things but we seriously don't need a bigger pump. I have aquarium pumps that can over perform ten D5 pumps put together, but what is the point? As long your water moves fast enough so that it doesn't rise by 2C between each component, it is good enough. But that is an incredibly low bar to clear so that's why you don't see larger pumps on the market. It is just going to be loud for no reason.

Here is where I disagree. 1) performance security of backup in case of fail, always nice- but yes not needed. 2) Purpose of series pumps is NOT flow. Flow is consistent from start to end of loop. Does not vary. What causes flow to reduce is restriction. In order of impact: CPU, GPU, tubing, rads, fittings. dual pumps compensate for loss of pressure, called head pressure, and measured in bars h20. maintaining pressure is what allows flow to maintain a high rate. So there is a purpose of dual pumps, particularly when getting into adding CPU, multi gpu, mobo blocks, ram, and hdd, plus the extra tubing length to reach everything (big impact there). A regular CPU/singleGPU loop is more than fine on one D5. as far as noise.... not sure what pumps you are using, but mine in my daughters system, 2 D5 on setting 3 are inaudible. Of course, like the bay res, I used decoupling material 😉 Be silly not to really. If you have massive noise, either a)air trapped b)not using decoupler c) bad pump


I would suggest that back rad be an exhaust. Front/bottom intake, top/back exhaust - normal case airflow.

 

[rofl_my_waffle]

I maintain my stance on the dual pump res being absolutely useless. Having two pump does improve pressure but only by a little. Probably so little companies were too embarrassed to publish benchmarks.

If you are really struggling for pressure, just run dual loops. It is vastly superior.

 

[Buzz247]

http://martinsliquidlab.org/2011/04/26/pump-setup-series-vs-parallel/2/
Matinlabs seems to support my statements. I understand what you are getting at, but this is proof that there is purpose to dual pump. It even states in the conclusion:

 "would also advise that dual pumps is not something that will normally net large measurable temperature gains, it’s generally reserved for those that are in search of that last degree in performance…or for those with extremely large, complex, and restrictive loops."

Which is what is was pointing out in OP case

 

[tinmann]

I had a single loop in a Corsair 800d sans the north and south bridge block with a Koolance 452x2 dual bay res, 2 Liang D5 pumps, Feser 360 on the top and two 140mm Black Ice SR1 rads like the OP has his 140's setup and got rid of the dual bay and 2 pumps in a hurry for a FrozenQ Fusion 250mm and a single D5. That was for an i5 2500K/GTX480 SLI config. I would also advise to stay away from the dual bay res and two pumps but it's comes down to your personal preferences.
You could save some money going this route though and it looks cooler in my opinion. The Bitspower Dual / Single D5 Top Upgrade Kit 250 - Black. http://www.frozencpu.com/products/16076/ex-res-369/Bitspower_Dual_Single_D5_Top_Upgrade_Kit_250_-_Black_BP-D5TOPUK250P-BKBKCL_.html?tl=g30c97s152
You would need to buy a pump top also.