280 vs 360 AIO

[ModifiedPhotoGraphics]

As the title suggests, i've read most of the reviews and tests online regarding numerous AIO coolers and until I decide to go with a custom loop again I was going to go with an easy to install and slightly lower cost AIO in the meantime. I've narrowed my search down to either the Corsair H115i or H150i to get me by for probably a year or so until I upgrade.

Currently I am still piecing together my new system, but the case I have purchased for the build is a Lian Li PC-O11 Dynamic which has room for a 280 in the top or a 360 in the top or side. I don't actually have a board or CPU picked out yet because I am patiently waiting to see what Intel drops in a few weeks (and how long that delay may be). Assuming I can't get a 9th Gen before the end of Oct, I'll likely go with an 8600k or a discounted 8086 to factor out some of the silicone lottery chance for a little more OC headroom.

It seems that the cooling capacity of both is similar, sometimes even leaning in favor of the wider but slightly shorter 280mm cooler. I suspect this may be due to higher static pressure of the larger 140mm fans. I've also read that it is slightly quieter (for the same reason). Price isn't my main concern between the two. But I certainly wanted to keep it under the $200 range which both accommodate just fine. Thoughts?

[ChalkChalkson]

Ok, cooling is a topic I could talk about for hours, so please stop me if I go overboard

The question of 280 vs 360 is pretty interesting in a few different ways:

 

1: Cooling Capacity

1.1 Background:

As you probably know a good way to think of cooling is in terms of little heat packages flowing like cars through traffic. If you want to cool say 90W from a CPU, you can imagine 90 cars (á 1J) coming out of your CPU every second. They need to move through the heat spreader, the cold plate, the water, the metal of the fins and finally into the air. The more area they move through the easier the heat can move, think of adding more lanes to a road. Some materials are easier to move through than others, think of aluminium as an asphalt and Intel's TIM as a dirt road. The final thing is the temperature difference; when the heat cars need to move through a thin slice of material (or from one to another) think of their speed as depending on the difference in temperature between the two ends (and the material). This means that for every meter of heat transfer through a given object you need more temperature difference with the increase being linea. Fun Fact: heatpipes or the water in your loop would be like a road that is also a conveyor belt.

 

1.2 What that actually means to your case:

When you compare two radiators, you need to think of the cars moving from your water into the air, as the materials are pretty much the same, as is the power of your CPU, so only the area impacts the temperature significantly. And if you want to lower your thermals, you want to pick the radiator with more surface area.

 

1.3 Radiator areas

So, what is the area of a 120x360 or a 140x280 radiator? Might sound like a trick question, but it is important to remember that the radiator is more than a solid box, it has fins and those do the actual thermal transfer. So you would need to find out how many fins there are per cm² and how large each fin is. But I am pretty sure that, if you are comparing two radiators out of the same product line, that those are equal. So here, in this specific case, just multiplying 120mm x 360mm (= 432cm²) and 140mm x 280mm (= 392cm²) and find that the 360 should give you around 10% more surface area. And thus ~10% lower temperatures.

 

2: Fans

Quote

I suspect this may be due to higher static pressure of the larger 140mm fans

The larger the fan the slower the static pressure. Think about it this way: look at a small part of the fan at the rim, the force applied to it is the static pressure of the fan, this force is now directed along the fan blade, meaning a part of it tries to stop the fan from spinning. The torque the motor needs to overcome that force is just the force multiplied with the fan blade radius. So the longer the fan blades the less pressure the motor can sustain.

What does increase is the amount of air shuved through the radiator. I got quite intrigued by your description and did some maths. Turns out, comapring the two setups gives you the following equality:

A\cdot T\cdot (H + \frac{v}{c}(exp(-\frac{cH}{v})-1))= constant

So, no matter what setup you are using, if the fans can manage the pressure (and if not it'd favor the smaller fans) area and temperature are still inversely proportional to each other.

 

The only thing that could make the 280 quieter at the same cooling performance is fan quality (assuming the radiators themselves have equal quality).

 

3: My suggestion

10% isn't a ton, but can ammount to 5K or so. If you care about performance deltas like that (ie you consider delidding) go for the 360, otherwise pick based on the spot you'd rather have the radiator

 

 

EDIT:

Dammit! When I saw LaTeX in the code box, I was filled with joy, that I could insert LaTeX into LTT forum posts, but at last, writing maths here still sucks

[ModifiedPhotoGraphics]

Good answer. It sounds like it's basically a wash depending on where I want to mount the rad. And since the 360 fits in more than one location, it makes a little more sense to me. I'm not sure if the Corsair fittings can be removed so I can eventually re-use the radiator or not for an open loop setup, but its inexpensive enough I could always re-purpose it for another system or give it to a friend once I do upgrade.

[Turtle Rig]

I feel like Im in science class in school.  Your very smart ChalkChalkson, wow,,, very impressive.  I have the 115i pro ,,,, but at that time I had a choice for the 360 ,, however my case has one spot for radiator and that is on the top,, and supports up to 280mm .  20 bucks extra is nothing, but ya its a bummer,  But let me warn you OP,  watch out for Corsair,, the pump sounds like a jet / cricket ,,,,,,, and the fns make cricket stupid sound on top of the air sound.  People told me its defective,, literally Ive shut off the rad fans to zero rpm,, and stopped my 2 case fans,, and my PSU fan isnt spinning its at 0,,and video card of course at 33 percent fan speed is silent.  I don't know why corsair put horrible fans like this,, a fan should just make air noise,, nothing other anomolies ,, its a disaster,, so in desktop I put it to quiet mode,, it makes little noise like 500rpm ,, but still the pump is a disaster.  Do you guys think its because I installed it the wrong way.  the tubes are at the bottom towards video card,, so there a curve,, then it goes up to the rad,  Changing this might kill the noise you think ? so the tubes are facing the rad,,, hmmm very annoying I used to have a silent system with the side case door open a hyper 212 and a silent custom made fan which make zero noise at 600rpm and just one fan no push.. I heard nothing,, so comforting,, then I get this case that says its quiet and it sounds like a jet the exhaust fan,, The fan I put has option for high or low,, at high its 1100 rpm and you hear its loud,, but doesnt make stupid noises cricket weird noises,, I put it on low and its silent,, all my noise is from the stupid pump,,, YOu guys thing its the positioning of it,, since the tubes are down instead of up towards rads. hmmm.  Thanks for reading guys.

 

[ModifiedPhotoGraphics]

Turtle, thanks for your feedback. I actually intend to replace the fans it comes with anyhow with ones I know are very quiet but will still work well. I might actually purchase the cooler locally despite paying a little extra so that I can test it out before installing to be sure the pump doesn't make any funky noises.

How long have you had yours installed? Did it make those noises since it was new or only after a specific amount of time?

[Turtle Rig]

18 hours ago, ModifiedPhotoGraphics said:

Turtle, thanks for your feedback. I actually intend to replace the fans it comes with anyhow with ones I know are very quiet but will still work well. I might actually purchase the cooler locally despite paying a little extra so that I can test it out before installing to be sure the pump doesn't make any funky noises.

How long have you had yours installed? Did it make those noises since it was new or only after a specific amount of time?

Hey ModifiedPhotoGraphics my friend. about 3 months I think and it was always like this.  At first this Corsair case which says silent had a exhaust fan of 1100rpm that sounded like a jet so the sound over took the pump noise.  So I put another exhaust fan at 600rpm and I don't hear a thing.  But when I put my rad fans to zero rpm "BTW thats the cool part of Corair products,, you use the iLink software and monitor temps and fans and pump,, You can change it all. no PWM needed.  I want to make a video of the sound for you.  When I say its annoying sounding and loud its a understatement,, its a disaster,,, WIth all fans at zero rpm you feel like your rig is gonna explode and crickets are going to come out of it.  My ears are sensitive so I can pick up fast.  I mean litearlly 3 1200rpm quiet fans like noctua will sound nothing like what this pump sounds like.. its not air noise of cousre,, its much much worse... Its unacceptable. Oh and the Rad fans, don't get me started on those.. anything above 600rpm and you got nasty cricket chrrrrrrrrrr noise I cant explain it.  Its not air noise its as if the bearing is botched or something.  I called Corsair and they say send it back, but although Im technical Im not technical with my hands and leave it up to my old man to do it, I don't wanna bother him.  So Im dealing with it.  At performance mode the fans are 1200rpm and it sounds like a jet.  But I only put the fans up,, when I game, and I wear HP's so its ok, not bothersome.  In desktop I set fans to like 450 for the first one which seems to make more noise then the second one.. and 600rpm for second one,,, you can hear it,, and can clearly hear the pump noise.  Look, one thing thats cool about Corsair is this.    Also it does a good job of cooling I had my vcore at 1.48 but recently botched my CPU its degraded after 6 years of abuse and OCes.  If your going to use 1.360v you will be pleased.  But there was a time before I ran prime95 and aida with 1.46v, but the fans must spin full speed same with pump,, Although I noticed the pump at 1100rpm and 2100rpm sound exactly the same but at 2800rpm its very nasty.  Plus 2100 or 2800rpm it gives the same temps which is nice.  Because 2800rpm is disasster which it already is at any speed.  Its really nice you can change the color of the block / pump,,, I don't have a clear side panel,, its closed, I sorta don't wanna get distracted, I like black and just simple door.  the RGB is really cool the iLink software is really cool.  Don't forget to read instructions on how to connect the iLInk its fairly simple.  I seen people complain the pump of this unit but different noise then mine,, a very nasty noise lol, in which case you can RMA, their in California btw.  Also my top has room for 280mm  rad but honestly your temps depend on your room temp.  If your in a hot room no matter how many fans you put or how big the Rad is the temps will be higher.  At end of the day the liquid temp has a lot to do with what temp your room is at.  74F is perfect, any lower the temps go down slightly.  I feel like my unit may be defective or maybe not.