Running two radiators? Will it be ok?

[johan851]

The water carries the spent energy (heat) from the CPU to the rad where it (heat) is then transfered to the air. If your block is doing it's job, there should be quite a bit of heat transfered to the water. In turn if the rad/fan is doing its job most of that heat should be transfered to the ambient room.....

According to some good calculations, it's about .5* C at the very most. Probably less. Really, it's been proven time and again - it doesn't matter. Route your tubing in the most convenient manner.

Where has this been proven. When I am gaming for long periods of time, the exhaust from my rad fan is quite warm. I can actually feel that the hoses are warmer....

Let me dig up a link. But first, realize that just because the water in your loop heats up, the water is still pretty much the same temperature at every point in your loop. Your tubing can surely be noticably warmer, but is the tubing going into the CPU block cooler than the tubing coming out?

Also, warm air coming off of your radiators DOES mean that heat is being dissipated - you're right. But air has a much lower heat capacity than water (this is why watercooling does a better job) and a small temperature decrease in water will produce a comparitively larger temperature increase for the given volume of air it is dissipated into. So even though the air seems significantly warmer, it's not cooling the water to the same "felt" degree.

Here's the info you requested. The data is for a pump, but the equation can be reworked for a higher heat load.

How about we inject a little bit of science into the equation eh?

Let's assume we have a Danner Mag 3, being a 35W pump. In actuality the pump will draw a low less power, but let's run with 35W.

Let's assume that the pump dumps all 35W of its power as heat into the water as the water flows through the pump.

Water has a thermal capacity of 4186 J/kg°C. Water has a density of 1.00

Let's assume that the flow rates through the system is 2GPM, or 7.5LPM, which is fairly reasonable given that pump and a moderate-high restriction block, or two low-moderate restriction blocks, and a low-restriction radiator.

Per second, 7.5/60 = 0.125l, or 0.125kg of water flows through the pump, for a total thermal capacity of 4186 * 0.125 = ~523W/°C

Keeping that the pump dumps 35W of heat into the water, then the water will rise by 35/523 = 0.067°C as it flows through the pump.

So the difference between having the radiator before/after the pump is just 0.067°C

So there's the mathematical/physics way to disprove the misconception.

So for a 100w heatload (which is significant) you'll see about .19* C on the other side of the waterblock. That makes it about .4* C if you halve the flowrate. As you can see, with a typical loop, getting a difference of more than .5*C is pretty tough, especially when you consider that some of the CPU's heat is dissipated through surrounding circuitry.

2 Loops would work great. Again I was thinking CPU> Rad> Vid> Pump> Rad> Cpu

I don't see why people think two loops is best. It's twice the pump heat overall, and you won't be using your radiators as efficiently as you would in a single loop. It's also creates more clutter and doubles your chances of pump failure, plus you need to worry about the extra cost of another pump and the extra power draw on your system. The only gain is a small increase in flowrate due to lower restriction - likely not enough to offset the performance decrease from the factors mentioned above.

To the OP:
A single Black Ice XtremeII should work just fine. You could add another radiator, but the affects of having would likely be very little, if at all noticable. If it were me, I would reject having the second radiator on the grounds of the lack of performance increase, but would be even more strongly against the idea due to the hassle and inconvenience it would cause. Sometimes it's just a pain to add things like that to the loop. If there's one thing I've learned from watercooling over the last 3.5 years or so, it's KEEP IT SIMPLE.

 

[96s10]

Alright once again before I make the final decision. It'll be cooling two EVGA 7800GTX KO's + a FX-55. There will be Maze 4's on the 78's and mabye a TDX or if theres a better one for the cpu.

So if one 120x2 black ice radiator can handle that then I guess I'll go that route!

Thanks guys!

 

[diehrd]

Alright once again before I make the final decision. It'll be cooling two EVGA 7800GTX KO's + a FX-55. There will be Maze 4's on the 78's and mabye a TDX or if theres a better one for the cpu.

So if one 120x2 black ice radiator can handle that then I guess I'll go that route!

Thanks guys!

It can handle it easily.

 

[samuknow]

Awsome info....Thanks Johan851. Bad Maniac I was not trying to argue just didn't make much since to me....

Again after all this time here, I have learned yet another tid bit.....

You state a second rad would yield minimal performance increase. But yet I see huge radiators witt 3 120s on them. Isn't it all about surface area when dissapating the heat from the water to the air? If I do not have room for a tripple 120 rad wouldn't 2 single 120s be better than one? I am seeing this more and more on water cooling sites. Is a rad that efficent at removing the heat from the water?

 

[pwnt by pat]

actually you can, you can back mount it or mount it on the bottom and have some tall feet for the case.

Emphasize the word in

Sure you can mount it outside of the case if you want but it looks tacky and you lose a lot of flexability on where to put the case and ease of movement.

 

[Perseus]

See I've never had a radiator before so I have no idea what to expect??

So a 2x120mm style radiator will work?? If I dont need the second then I wont get it? I just dont think I could fit a 3x120 on the top of the lian li 65B.

http://www.newegg.com/Product/Product.asp?Item=N82E16811112040

I replaced a BIMII and BIX with a 120.3 and the performance difference in terms of cooling is VERY pronounced. My CPU is within 3c of ambient and my video cards are 10c above, both idle temps. I wish I could tell you for sure what the difference is, but TBH so many things have changed that I'm not quite sure. I SUSPECT that it has at least something to do with having a large single rad.

 

[johan851]

You state a second rad would yield minimal performance increase. But yet I see huge radiators witt 3 120s on them. Isn't it all about surface area when dissapating the heat from the water to the air? If I do not have room for a tripple 120 rad wouldn't 2 single 120s be better than one? I am seeing this more and more on water cooling sites. Is a rad that efficent at removing the heat from the water?

Like I mentioned before, convenience is a big factor in choosing what radiator(s) to use. Usually larger rads do yield better results, and having a larger fan will also allow you to use quieter fans, but using two rads can be a pain and will actually cause a littl e more pressure drop than a single larger rad. Plus, the second rad in this case is a dual 80mm rad - it just doesn't seem like it's worth it, at least in my opinion. You probably would see a difference of a couple degrees with the second rad, but yes, radiators ARE that effective in cooling down water.

I replaced a BIMII and BIX with a 120.3 and the performance difference in terms of cooling is VERY pronounced.

But that's a single 120mm rad and a dual 80mm rad - not a whole lot of cooling capacity in the first place. It's a different scenario than this one, where we're starting with a dual 120mm.

So...yeah, you'd probably see a performance increase from two rads, but I wouldn't recommend it due to extra cost, plumbing hassle, and minimal performance increase over a single dual 120mm rad.

 

[Perseus]

But that's a single 120mm rad and a dual 80mm rad - not a whole lot of cooling capacity in the first place.

Except just the opposite would SEEM to be true. In terms of surface area both rads together should equal a 120.2 rad of like construction. From what I've seem so far from my new configuration though, two rads just didn't come close.

 

[johan851]

Maybe less airflow and a larger dead spot on the BIM II? *shrug* What waterblock and pump? Or it could've been remounting the block made a difference too...

It's usually pretty hard to tell, especially with mobo temp sensors.

 

[samuknow]

This has definatly posed some interesting questions....

From past experience...not all math equations work out the same in "real" life...I am going to try a few combinations and see what real world results I get. So many variables can have positive or negative results. ie., Bigger pump can help or hurt performance depanding on the block ir blocks used. Two rads give more surface area but possibly reduced flow and possibly hurt performance.....

96s10, I did not mean to run away with this....This question has been on my mind for some time also...just remember, not all things are absolute

 

[Perseus]

Maybe less airflow and a larger dead spot on the BIM II? *shrug* What waterblock and pump? Or it could've been remounting the block made a difference too...

It's usually pretty hard to tell, especially with mobo temp sensors.

I wish I knew for sure. It's a good mystery, but still a mystery. My new setup uses a Storm and two D5's, plus the exhaust flow from the rad goes to the Storm intake. I was using a TDX and a single D4. It's possible that the mb sensor is wrong, but it tracks ambient fairly close. It sounds like I have a good reason to buy an inline temp probe, if I can find one that'll fit this huge American-style tubing.

 

[metloaf]

I thought about a dual rad setup as well however after some research I settled with a good size Ford heater core which also happened to be free. It came in good condition and the guy I got it from is a mechanic and even leak tested it and cleaned it up a bit. I think it should work out well. the dimensions are, 9"Lx6"Wx2"thick. I am planning to mount 2 92mm fans to it or 1 120mm fan, I haven't decided on that yet.

 

[johan851]

^ I'm still using dual heatercores, and I've always liked them. Might not be the best thing in the world, but they definitely get the job done. And wonderfully inexpensive. In terms of bang for the buck, they're still the best choice in my opinion.

My new setup uses a Storm and two D5's, plus the exhaust flow from the rad goes to the Storm intake. I was using a TDX and a single D4

Whoa. I thought you were just doing a radiator switch up. You switched to a better waterblock, then about doubled the amount of pump pressure going into a block that just loves it. Add a little radiator to make up for the extra pump heat dumped into the loop...THERE'S the difference.

 

[Perseus]

Whoa. I thought you were just doing a radiator switch up. You switched to a better waterblock, then about doubled the amount of pump pressure going into a block that just loves it. Add a little radiator to make up for the extra pump heat dumped into the loop...THERE'S the difference.

Yeah, I guess I should have mentioned that everthing was new. Looks like I finally got it right!

 

[96s10]

96s10, I did not mean to run away with this....This question has been on my mind for some time also...just remember, not all things are absolute

It's cool I got my info.