Newbie fan-placement question

[jektal]

I’ve been building my own PCs for >15 years, but am finally setting up my first watercooled system. My plan (parts are en route) is to use a Corsair 450D with two 2x140mm radiators on separate loops: one shared reservoir and two pumps in parallel. One pump will push to the top radiator, then the CPU (i7 4930K), then back to the reservoir. The other pump will push to the front radiator, then the GPUs (two R9 290Xs) in sequence/serial then back to the reservoir.

My question is really about the fans. I’d definitely like to have the top radiator blowing upwards out of the case (heat rises, dust settles), and in a traditional air-cooled system I’d have the front fans blowing in to maximize air flow through the tower, but I’m a bit worried about saturating the inside of the case with GPU-radiator-warmed air. Given the case’s rear and bottom openings/fan mounts, could I have both radiators blowing out of the case and rely on the negative pressure inside the case to draw air in through those openings?

If I have both radiators blowing out of the case, should I add an intake fan on the rear of the case? Between the front radiator and PSU I don’t expect to have room for a fan on the bottom.

And finally, how bad of an idea would it be to only mount one fan 140mm fan on a 2x140 radiator? I’m planning on putting two fans on each radiator, but just wondering if taking one fan off (less noise, more space) would be catastrophic to the radiator’s cooling capability or not.

 

[Robert17]

The 290Xs generate a lot of heat, so aggressive cooling will matter. I have my rads' fans blowing all that extricated heat out of the case, compensate with inbound air wherever makes sense after that.

 

[Nebulous]

Those 290X's are going to be dumping some serious heat in the loop alone. I'm thinking you should get a larger case with a larger rad just for those. The chip won't need that much rad, but those cards will.

A triple 140 rad for the cards and a dual 140 for the chip.

Also you're going to need alot of airflow so you'll need the most fans you can mount in that case for that type of cooling.

Have you looked at other cases besides the Corsair 450D?

Fans are typically set up like so:

Front, bottom = Intakes
Top, back =Exhaust

 

[jektal]

...compensate with inbound air wherever makes sense after that.

Thanks. Will I need to force air in with an intake fan, or will a passive draw in do just as well? I'm trying to keep noise manageable.

 

[Daddyjaxx]

Noise is the matter of the fans. Get rads with low fins per inch and you can get fans lower than 19 DB.

 

[jektal]

... The chip won't need that much rad, but those cards will....

Yeah, but its a shared/single reservoir (Alphacool Repack Dual 5.25"), so the heat should balance throughout the system, right?

 

[ATMINSIDE]

Yeah, but its a shared/single reservoir (Alphacool Repack Dual 5.25"), so the heat should balance throughout the system, right?

That doesn't matter if you don't have enough radiator to remove all the heat...
I would want 5.140 or 6.120 at a bare minimum for that rig. Even with that it would take some serious fans to keep up.

 

[Daddyjaxx]

Yes, if you are sharing the water anyway, why not just run one loop? You do need more rad for those cards as everyone has pointed out. More rad is better than not enough.

 

[jektal]

Noise is the matter of the fans. Get rads with low fins per inch and you can get fans lower than 19 DB.

Done: Swiftech MCRx40-QP "Quiet Power" radiators (12 FPI) and COUGAR CF-V14S Vortex Hyper-Spin fans (17.9dB).

Though now I'm starting to wonder if that's going to be enough heat removal.

 

[Daddyjaxx]

You still need the rads to support it. For example, I plan on running 3 x 120.4 for three 780TI's. Since I have so many rads, I can have quiet fans.

 

[Nebulous]

Done: Swiftech MCRx40-QP "Quiet Power" radiators (12 FPI) and COUGAR CF-V14S Vortex Hyper-Spin fans (17.9dB).

Though now I'm starting to wonder if that's going to be enough heat removal.

How many did you get and what size? Single, dual or triple 140's? Because with just 2x dual 140's rads, that won't be enough raddage.

 

[RnRollie]

as above you do not have enough rad, the two R9's alone already justify 120.5

Simplified rule: 120.1 per 100 watt, thus:
CPU: 120.1 minimum, 120.2 to keep it silent
GPU: 120.2 minimum, 120.3 to keep it silent (120.4 if R9)

So, in your case 120.2 + 120.3 + 120.3 = 120.8 that is A LOT of radiator
Suitable cases: Phanteks Enthoo PRIMO, Corsair 900D
OR.. get a nice small, sexy case and use an external radiator like the MO-RA3 or the Phobya NOVA

Top of the range Rads: Alphacool Nexxos UT60, XT45, ST30 ; XSPC RX-series

Since you're taking about shared reservoir ... water mixing doesn't matter, the loop stabilises at some point. However, if you were to use as much radiator as proposed (120.8), you'ld be better to setup the pumps in SERIES, not parallel.

Noticed that i didn't refer to 140mm rads? That is because there is still a lack of GOOD 140mm fans which are suited for a radiator. By all means, go for 140mm radiators, but be prepared to put all of them with 140mm fans in push/pull or to use 120mm fans with 140/120mm converting shrouds.

And .. good fans dont come cheap, be prepared to look at fans that cost + $25,- a piece.

.

 

[jektal]

Alright well I'll see what I can arrange...

If they can fit, would adding 2 separate 120mm rads potentially be enough (as intake, with fans that double the CFM of the 4 exhaust radiator fans)?

And what's the best way to keep track of temps and determine when you're okay/in trouble?

 

[Daddyjaxx]

RealTemp, but if you're in trouble with Intel, it will throttle the CPU or shut off the system as long as you don't mess with the thermal protection in the BIOS. I saw a video years ago where they removed the Intel's fan and it kept going. The AMD CPU fried. I would hope by now they have added thermal protection especially with CPU's requiring 230 watts.

 

[GTXJackBauer]

Welcome to OCFs.

My plan (parts are en route) is to use a Corsair 450D with two 2x140mm radiators on separate loops: one shared reservoir and two pumps in parallel. One pump will push to the top radiator, then the CPU (i7 4930K), then back to the reservoir. The other pump will push to the front radiator, then the GPUs (two R9 290Xs) in sequence/serial then back to the reservoir.

Are you implying that all your water cooling components including the case are already purchased and shipped on their way to you? Just want to make sure since everyone is giving you advice on other gear. We'll just work with what you already ordered and is on its way, if that is the case.

 

[Supertrucker]

If you don't require every last degree, 120.4 is plenty of rad with moderately quiet 1450rpm gentle typhoons in push/pull. I lost exactly 0mhz cpu or gpu going from 120.6(push gentle typhoon ap-14s) & 140.2(push lian li 140s) to just 120.4(ap-14 push/pull), just went up about 5℃ load temp.

 

[BruceUSA]

You need bigger case and more radiators. I am running this same combo as yours. But I am running a simple single loop with 120.10 Black Ice GTX radiators and Delta fans. My 2x 290X oc never get pass 47c in 3Dmark/Heaven benching. You can see some photos here.

http://www.overclockers.com/forums/showthread.php?t=749350

 

[RnRollie]

If you don't require every last degree, 120.4 is plenty of rad with moderately quiet 1450rpm gentle typhoons in push/pull. I lost exactly 0mhz cpu or gpu going from 120.6(push gentle typhoon ap-14s) & 140.2(push lian li 140s) to just 120.4(ap-14 push/pull), just went up about 5℃ load temp.

And your loop temp is now what when running Heaven + Prime ?

 

[jektal]

Are you implying that all your water cooling components including the case are already purchased and shipped on their way to you?

I'm stating that, yes :/ Will need to try to add what I can to what I have...

 

[RnRollie]

I'm stating that, yes :/ Will need to try to add what I can to what I have...

gonna need decent fans then