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Discussion Starter · #1 ·
Hi all

I'm building my new main pc in a new Corsair Obsidian 800d, but have some difficulty in designing the loop. Building has not yet started, but once I have got answer to a few questions, I will start building. The rig is designed for silent operation and sufficient performance, not for top performance.

My current plan is this:
531

The blue arrows are cold air, the red arrows are warm air. The purple lines are tubing and the flow direction is indicated

The first point of which I'm uncertain is the direction of the fans on the radiator. My current plan is to have them as inputs (covered by a dust filter of course), and thereby achieving:
  1. Cold air from outside cools the radiator
  2. Air (hotter than ambient, but not too hot) to cool the memory and chipset. Memory is my main concern. It's Corsair Vengeance 1600 MHz, 16GB, with heat sinks. It's designed to work with passive cooling, but I would sleep better at night with a little bit of air passing past them
  3. Positive pressure inside the case to avoid unfiltered air to be sucked in through holes
The top three fans will be low-RPM fans pushing little air. Probably the rear and bottom fan must be replaced with something more powerful. The HDD cage fan will most likely remain since HDDs are not that sensitive to temperatures. Has anyone tried a similar setup? Will warm air build up inside the case, or is it possible to remove all warm air with one rear exhaust fan?

The second point of which I'm in doubt is the reservoir. I have a bay reservoir, and would like the reservoir to be in the top bay as the highest point in the loop for easy filling and bleeding. Unfortunately, there simply isn't enough room for the radiator, the reservoir and the tubing to connect them. The reservoir must therefore be placed below the radiator. Am I correct in assuming that it would be impossible to fill or bleed the system without having long enough tubing to take out the reservoir, raise it above the radiator, fill and bleed the system, seal it off, and put the reservoid back in?

I fear that tubing of of that length will get kinks, so I was thinking about connecting a fillport to the top of the reservoir. Then I can fill and bleed the system without removing the reservoir, right? And the combination of the flat roof in the reservoir and the tubing up to the fillport would be similar to that of a t-line, so I can fill the entire reservoir, trap air bubbles in the tubing and avoid them getting sucked back into the pump? This has been a problem with my current rig, so I would like to remove air from the reservoir. Will it be possible to get all air out from the radiator this way or will there be air bubbles in the radiator since it's the highest point in the loop?

The radiator also has a third hole for mounting a G1/4" compression fitting. This hole is located on the upper left side of the radiator (when the radiator is mounted as shown in my figure), and this hole is higher than the reservoir. Should I use this hole as fillport instead?

Edit: any tips, advice, comments and suggestions for improvements are most welcome!
 

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The Computer Guy
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I would have the top fans blowing up and out the case,And I would do it as a push/pull configuration.
 

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Discussion Starter · #3 ·
And make the rear fan an intake fan perhaps? Will I still get some air flowing over my memory banks as well? I really would like just a little flow over them, but I am not willing to use a ram cooler (most of them have small fans and make too much noise)
 

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The Computer Guy
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Is there a fan in the front of that case?
If so,Make the side/front inlets and back/top outputs.
This way air will flow across the motherboard and memory.
 

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Discussion Starter · #5 ·
Unfortunately there isn't a fan in front (one can't get everything, I'm afraid). I opted for a case with room for many 5 1/4" and 3 1/2" bays since I need those more than cooling in front. But the side panel can always be modded to allow a fan or two
 

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The Computer Guy
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Modding the side panel to accommodate more than 1x 120mm fan would work fine.
 

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Discussion Starter · #8 ·
Quote:
Originally Posted by Billy O View Post

I think pull only on top of the case should be fine for that 360 rad. No need to blow hot air in.
Why pull on top? My (perhaps naive) tought would have been to place the fans under the radiator and push air upward. Is it best to have the fans on top to get the radiator on a lower level, or does it matter?
 

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Discussion Starter · #11 ·
Yes, it's a low fin per inch radiator; a 360 from Coolgate. I plan on using BlackSilentPro fans from Noiseblocker. Fans will be connected to a fan controller to keep them as silent as possible. Most likely I will mount the radiator to the case and put the fans under it in a push configuration to push air upwards. Or should I keep the fans where they are in the figure in a pull configuration? Or does it really matter?

The reason I'm asking all these stupid questions is that I would like to get it right the first time
 

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Discussion Starter · #13 ·
Oh, I didn't know that; thanks for telling me. My fans will most likely get an operating point of about 900RPM, so I guess I'll keep them on top and pull air out of the case then.

That leaves only the question of the fillport, and building can begin
thumb.gif

Do I need that fillport? From my understanding, it would be impossible to fill the system without a fillport. I have read that a fillport should be connected to the highest point, but that would be the radiator. But I see from other threads that the most common place to put a fillport is to the reservoir?
 

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Quote:
Originally Posted by microman View Post

I unlike everyone else so far think that your drawing is perfect. I see no need to blow warm air through your radiator.
There have been few threads on this topic lately, and I think it's split down the middle now. I did intakes on both my rads in my 800D because I was thinking cooler air from outside would be better over the rad fins. I'm getting good temps... and my case seems to be exhausting internal air fine through the back and my modified side panel exhaust. I've seen people say they have good results the other way around.... so I think it's fine going either way. For me... logically... cooler air would be better through the rad fins... but I'm still new at water cooling.
 

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Discussion Starter · #17 ·
Quote:
Originally Posted by Los Hog View Post

if you have the slack in your tubing you can pull the res out to fill it
I'll keep that in mind. So far it doesn't seem likely that I can achieve such a slack without risking a kink in the tubing, but this can change when I actually start building and components finds their rightful place
Quote:
Originally Posted by microman View Post

I unlike everyone else so far think that your drawing is perfect. I see no need to blow warm air through your radiator.
Thank you! I'm very glad to hear that I am not insane to think about mounting the fans "opposite" of the standard orientation. I would like to try to avoid warm air over the radiator, but with both top and bottom fans blowing in, the only exhaust will be the rear fan, and my sole concern is to get efficient exhaust.
Quote:
Originally Posted by erayser View Post

There have been few threads on this topic lately
Do you have a link for me? I have been searching this forum, but haven't found anything? Or is the other threads on other forums?
Quote:
Originally Posted by erayser View Post

I did intakes on both my rads in my 800D (...) I'm getting good temps (...) seems to be exhausting internal air fine through the back and my modified side panel exhaust (...) For me... logically... cooler air would be better through the rad fins... but I'm still new at water cooling.
I've read your build log and seen your modified side panel(*), but couldn't find anything about radiator FPI or fan RPM? I am planning to have low FPI and low RPM, and it has been pointed out to me that I also need to fight convection of warm air raising up, and also fight the pressure from the bottom fans to get the warm air exhaused.

(*) Nice build by the way. I liked the black/white theme and all that awesome hardware
 

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I have tested both ways and posted results here before (using 12 calibrated dallas 1 wire probes, one in front of each fan intake measuring to 0.1C and multiple inside case), ie tested taking in cool air from rad and blowing this 1-2C warmer air into case versus using ~2-3C warmer air (especially heated by vrm/graphics cards etc) from inside case expelling through rad.

And not surprisingly you will get about 2-3C better cpu temps by using cooler air, like your picture in post 1, which after thoroughly testing is how I set mine up. And may be surprising to some, the internal case temps and mobo temps were either same or better by blowing this "warmer" rad air in to case vs blowing warmer air out of case, especially true if using push/pull as this allowed blowing air directly over ram/mobo. And it being warmer air is nonsense. For 25C ambient temps, the internal computer case temps were about 28C either way, but blowing air in had much better direct flow of this same temp air over mobo/ram etc, resultng in better component temps (moving air cools way better than stagnant air) though similar case ambient temps.

The only scenario that isnt better than your design in pic 1, is when you are water cooling both gpu and cpu + you fully load both with furmark and prime + fan speeds below 1200 rpms. Then your internal case temps, mobo temps, are better by expelling hot air through rad, though your cpu temps still suffer.
 

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Discussion Starter · #19 ·
Interresting! So if I use fans with ~1200RPM instead of my planned ~900 it is possible to use the design in my first post? The CPU loop will cool an intel i7-2600k, which I intend to overclock once everything is up and running stable. The GPU will not be overclocked(*). Most likely the GPU will not be cooled by water either. I plan on using a graphics card that is passively cooled(**) since I do not need the hard-core graphics and prefer silent operation. But the CPU needs to be cool since I plan to overclock it. Are you saying that my initial design could actually work?

(*) This will not be a gaming rig but an hard-core computing PC. It also has onboard graphics that will be cooled by air
(**) http://www.asus.com/Graphics_Cards/NVIDIA_Series/ENGT520_SILENTDI1GD3LP/
 

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Intake issue is easy to completely eradicate if you replace the window with a mesh panel. See here on the side of the case. I never really took a pic of my panel cuz well, it's not that big of a deal.

p1080102p.th.jpg
 
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