Radiator Questions

Hi, I'm new to these forums but I have been looking through a couple posts on watercooling. I recently just bought a computer with an i7 920 D0 and two 9800GTs (not overclocked) in SLi and they're "power efficent", whatever that means an am interested in starting watercooling :]

I haven't begun overclocking yet because from what I've read, the stock fan that comes with the i7 920 is pretty bad and I'm currently at 25C idle and up to 40C under some gaming and usage. I picked up a Swiftech Apogee GTZ from a nearby Microcenter and a MCP655-B.

I'm planning to get an XSPC RX240 to fit internally in my Antec 902, which will take up my drive bays because I dont use them anyways. So here are my questions :

1. Will the radiator be sufficent enough to support the i7 and the two videocards? I doubt it but the XSPC looks alot thicker and I only plan to OC up to 3.6-3.8GHz

2. I don't have much room to install pull shrouds so could I use the antec tricool fans (in the front) to use them as a push and some Scythe Gentle Typhoons as pull (without shrouds)? Would this cause any complications because they don't match up?

3. Whats the optminal Gentle Typhoon rpm model for the XSPC RX240? I've read that they are only need low-med fans. Would the AP-15 suffice? I would prefer to keep it silent and have it perform well too. (Wouldn't we all? )

What ambient temps?
What's the max fan speed you're willing to run? Tolerance for noise varies.
What CPU temps are you seeking for?

IMO, without the first 2 information, we will never ba able to tell you what radiator size is sufficient. Unfortunately, it's hard to answer the 2nd one. If you're living near the equator where aimbient temps are ~30C, and you're running 400rpm fans, then even a quad radiator might not be sufficient. Speaking of fans, I suggest Petra's yate loons. Cheap and good.

On top of that, the dual rad may be enough for the CPU, but I wouldn't trust it to do the CPU and 2 9800GT's. I have a triple rad for a Q6600 and a 9800GT, and although I don't have the loop set up yet, I am pretty sure the rad is enough to cool what I need it to. You are much better going with too much rad than not enough. The best thing to do is a lot of reading before jumping in and getting your feet wet. You will not regret it. Remember, water cooling is 90% studying, 10% doing.

My ambient temperature in my room is about 70F or 21C.

I was just hoping for the dba to be under 30ish? 2000rpm isnt that bad right? That should be pretty tolerable. Do the YL have enough static pressure to push through the RX240? It looks almost 2x the depth of the Swiftech radiators.

I haven't purchased any GPU blocks or anything but I was just wondering if my loop could pull it off. I probably will only use it for the CPU since my 9800GTs probably wont be OCed.

Also, I was going to try to keep the temps under 70C if possible, I dont want to overdo it since its plenty fast enough.

There are some simple charts at http://www.skinneelabs.com/

They will show what your resultant water temps (Delta T) will be with a specific heatload and different fans. A 120x2 is considered the minimum for a i7 920. If you live in a hot summer climate and want to overclock to 4.2 (if your chip will do it) you'll need a 120x3 for good temps. The GPUs will pump out another 250 watts of heat combined under load, but thats a far guessitimate. So your looking at about 500 watts I'd say in total.

2000 RPM is past the quiet limit pretty much. You should stay under 1200 or so for quiet operation. The RX240 is what we call a Low Fin Per Inch (FPI) rad. They perform well with low speed fans and respond well to high speed fans. Yate Loons are great fans for a rad. I run Medium Yates and fan control the RPMs to maybe 900 or so.


Keeping the load below 70 all depends on your air temps and your overclock, and the chip. So you CAN stay below 70C, but it just depends on how much raddage and noise you want to deal with. The cooler the rad water, the cooler your chip.
........................................

DT Temps

A delta measurement is used in many engineering terms in many disciplines. I guess it means the difference between two of the same thing.

In water-cooling it's simply the difference between the ambient air temps and the water temp on the outgoing side of the rad. Room temps vs. water temps. A better rad setup cools better. Load meaning heat created. Stable meaning the load has been running long enough so the loop is stabilized, heat is made; it is removed and run long enuff for the water temps to get to the max under a load.

If your ambients (air into the rad) are 60C and your water exiting the rad is 65C, you got a 5C DT. And it’s important you understand this simple concept. You need xx cooling for xx heat load for a resultant xx DT. Its how you decide what size radiators you need as a minimum for the loop to perform better than air, and what’s needed for really superior max over clocks.

So for example, in a water cooled loop you generate 200 watts of heat. Your block pulls heat into the water; the heat is dissipated into the air by the rad/fans. Skinnee and Martin came up with a great chart for rad test results. Make xx heat, run xx fans with xx radiator brand and size, your DT is xx.

The efficiency of the rad determines the residual heat in the water as it circulates. A rad cannot remove ALL the heat. Heck if that was true, running a rad with no heat load would cause the water to go all the way down to below freezing theoretically. A great Delta T is under 5C, meaning you got a big rad for your heat load. Medium DT is 10C, and 15C is getting bad. CPUs need lower DT than a GPU loop.

Ultimately lucky folks with cooler temps year round can go with lesser rads. People with high ambient might need bigger rads for the same final core temp on a CPU that someone in Norway vs. Samoa can get.

Hope that helps, it’s a simple explanation, I'm not a Thermodynamic engineer.


You'll need more rad for the GPUs, and cutting it close on just the CPU with your 120x2.

1. that rad will support the cpu alone and your overclocks with decent temps imo. i would grab another double 120mm rad if you want good temps for your cards.

2. you don't need any shrouds, well in your case it might help. but i wouldn't worry about them.



yes yate loons are great fans for rads and are used alot.

Agreed Spawn. The rad is enough depending on the fans used. Ambients and the OPs goals play a final part. I only know the GTs by the RPM. 1450 or 1850. The GTs at 1450 would be my choice, good for that rad.

so which ones do you guys recommend for the rad

- Yate Loons?
- Scythe GTs?

I'm currently debating between the two.

Conumdrum said:

There are some simple charts at http://www.skinneelabs.com/

Click to expand...

thank you for the link !! you da man !!

blu3phoenix said:

so which ones do you guys recommend for the rad

- Yate Loons?
- Scythe GTs?

I'm currently debating between the two.

Click to expand...

both will get the job done, from the sounds of it the gt's are really nice.


but if money is a concern i would opt for the yates.

I've got 4 GT 1450s on my rad. At the slowest speed they're very quiet (the hard disks idling are louder). At full speed they're noticeable but have an pleasing tonal quality but are by no means loud.

I think I will probably go with the Yates, seeing I am almost over budget for my build.
but the thing I was wondering was what model of Yates are people always talking about?

D12SL,M,H?

I was thinking the medium ones should be good enough since my rad has low fpi and I didnt want to get too low of airflow through the radiator and I figured a little bit more couldn't hurt.

EDIT: and Happy New Years OCers :]

i have the high speed yates running at 5v and they are near silent to me.

but the mediums should be fine for the reason you said.

Mediums are great. I use them on both of my low FPI rads. You'll probably run them at full speed when gaming, but when cruzin the web you can turn them down.

Great Cheap fan controller if you don't have one. I have two channels with 3 YL Mediums in parellel.
http://www.jab-tech.com/Sunbeam-5-1-4-Rheobus-Kit-BLACK-pr-2530.html

or build your own

http://www.thebestcasescenario.com/forum/showthread.php?p=274643#post274643

lol. I don't have enough room for a fan controller so

Mediums will run quietly enough right? If anything I can undervolt them to 7v or 5v.