• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

Going Against WC Conventional Wisdom

R

Rucker61

Limp Gawd
Joined
May 14, 2009
Messages
264
I'm a newbie looking to watercool my first system, and I've been reading a lot. The WC CW says to always pull cool air from outside across your radiator. As I try to design a two loop system with the cases I'm interested in, this seems to bring in a lot of hotter air into the case with no real good way to balance the airflow with exhaust.

Is there any reason not to use the rad cooling the GPUs to be the exhaust system? From what I've read, GPUs run hot anyway, especially the bigger ones, and if your main goal for water cooling your GPUs is to reduce noise rather than cut 40C from your temps, then using the exhaust from the CPU rad plus some other cool air intake should still allow the GPUs to run in the 60s/70s, right? If this is a feasible solution, it sure would make my WC design a lot easier.

What I'm looking to cool: i920 (OC to 4.0), EVGA x58 Northbridge/Southbridge on loop one. Loop two: EVGA 275s in SLI. I think with a little luck I can do this with two Black Ice GTX280s in/on a Cooler Master 590. I'm using a recording desk for my work space and there's 21" between bottom shelf and desk surface, so a mid-tower is ideal for this space.

I say two loops, but what kind of temps could I expect if I ran one big loop with a D5 variable as the single pump. According to one review, the 280 rad has the same flow resistance as the MCR320. For waterblocks I'm looking at the HK 3.0 LT/LD, NB/SB would be the Koolance x58 block, and a pair of x58 Koolance full coverage blocks for the two GPUs. Fans would be the 1900 rpm 140mm Scythes on a fan controller.
 
actually i think conventional wisdom is normally to exhaust air through the rad(s) for the same reason you just said. the air inside the case will be a couple degrees hotter than outside (less than if the cpu and gpus were air cooled, in which case it can be significantly hotter than outside temps.) and you dont shoot all that warm air into the case. just make sure that you have either a few air intake fans somewhere, or have plenty of mesh for cool air to flow in. its hard enough for fans to push air through rads as it is, so without a good source of cool air into the case it will be harder still for the fans to push a decent amount of air through the rads.
 
It is commonly done both ways and it is indisputable that providing the rad the coolest air possible works the best.

With one loop what you advise is not a good idea as the heat you removed from one rad basically is added back to the second one (in reduced cooling efficiency) and the entire loop would be affected.

With two completely seperate loops as you propose the effect is not as bad for exactly the reasons you mention, if you are not looking to attempt a cutting edge OC on the video cards they will run much cooler than air even with the warmer case air going through the rads.

So - little secret that is not really a secret. All engineering is a compromise.

Just make sure there truly is no way to pull ambient room air through both rads. Make double sure you have thought of all mounting possibilities that meet whatever other (looks) goals you have. I have built 8 WCed systems and there is not a single one that despite hours of planning etc that 10min after I got done I did not say "CRAP I should have done that another way".

Have you considered one rad in the top and one in the front both blowing in ? Looks like that would work with that case and will all the other fans working as exhaust it should do well. But anywho like I said everything is a compromise.
 
Last edited:
It is commonly done both ways and it is indisputable that providing the rad the coolest air possible works the best.
Click to expand...

This.

Never forget the difference between "Heat" and "Temperature." Heat is the total amount of thermal energy contained in an object, group of objects or substance. Temperature is the average "heat" of each molecule in said object or group thereof.

Since you're moving a large volume of air, at a high speed, through a large radiator, a lot of heat is moved without increasing the average temperature of each air molecule. This means that, if you can adaquately exhaust this warmed air with other case fans, you can get rid of it, even if it's dumped into your case.

But, your best bet is to keep the air moving through your radiator as "ambient" as possible. Using warm case air is a no-no, so sucking cold ambient air through the rad is often employed. Now, that's not to say you can't use case air through your radiator... But you have to make sure that this case air is as close to ambient as possible.

In my last setup, I had a top mounted radiator blowing air out of the case. There were so many vents in the case that case air was just as cold as ambient air.

In short, use your warm case air to cool your GPU's. It'll be fine. You'll STILL knock off a good 30c (at least!) from their temps.
 
I use a UFO with 2 loops. My cpu loop gets fresh air from outside, my GPU loop uses air from inside the case, through the rad, and exhausted out. I recently reversed it, and the temps were the same. As long as you have enough radiator, you wont notice enough difference to matter.
 
You must log in or register to reply here.
Back
Top