Stacking Radiators - bad idea?

A

AP2

[H]ard|Gawd
Joined
Jun 25, 2007
Messages
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I've been searching and some say its ok and some say forget about it.

This would be a dual loop configuration doing this: 140x60mm Rad (7 fpi) - 140mm fan - 140x60mm Rad (7 fpi)

1 140 rad would be for the GPU
1 140 rad would be for the CPU

Thoughts?
 
Yeah,

I wouldn't do this. You'll need more powerful fans to get the same flow through the radiators (more noise) and the benefit will be limited, as heat transfer depends on temperature difference. The bigger the difference in temperature between the radiator and the air being pushed through it, the more it will cool. (This is why we can never get below ambient, as the difference then is 0.)

The air may start out relatively cool when entering the first radiator, but when it enters the second it will be warmer, and thus will be less effective.

This is why more radiator surface area always beats thicker radiators, because you are always getting the coolest air possible.

Theoretically you could see a marginal benefit, but in practice I have found that it results in a lot more noise and the difference over just the single radiator is barely measurable.

TLDR: I wouldn't waste your money. Upgrade your case to something bigger and put more radiators in their own fan slots instead.
 
Why would it be a bad idea? I think it's at least worth a shot. Cars routinely stack the radiator with the evaporator and it works well. The heat capacity of water is so high I don't think it would make that much of a difference.
 
It will work but like others said you going to lose efficiency. You will need more powerful fans to get the same results as having them separate. That will result in more noise. If you can deal with the loss of efficiency and noise then go for it.
 
7 fpi is pretty low, with a reasonable pressure fan it should be fine. My only gripe with stacking radiators is that you're trying to cool one radiator with the hot air of the other. It'll still work, and it will improve temps, but not by as much as two separate radiators pulling in their own cool air.

If you're gonna do it, I recommend stacking them this way: CPU rad -> fan -> GPU rad, arrows indicating airflow direction. This is so the CPU doesn't get soaked with the GPU's heat. It works better this way than vice versa.
 
Thats for confirming guys! I'll give this a shot as I only need to buy a few fittings and a 140mm fan. I'm not overclocking or anything, but this will be for a 8700K and 1080 mini (non ti).

or do you guys think a single 120mm x73mm rad would work better?

as you guys can tell I'm trying to cram some water cooing into a small case, if all else fails I'll just stick to air.
 
Emission said:
7 fpi is pretty low, with a reasonable pressure fan it should be fine. My only gripe with stacking radiators is that you're trying to cool one radiator with the hot air of the other. It'll still work, and it will improve temps, but not by as much as two separate radiators pulling in their own cool air.

If you're gonna do it, I recommend stacking them this way: CPU rad -> fan -> GPU rad, arrows indicating airflow direction. This is so the CPU doesn't get soaked with the GPU's heat. It works better this way than vice versa.
Click to expand...

Ill set it up that way and see where it goes.
 
AP2 said:
Thats for confirming guys! I'll give this a shot as I only need to buy a few fittings and a 140mm fan. I'm not overclocking or anything, but this will be for a 8700K and 1080 mini (non ti).

or do you guys think a single 120mm x73mm rad would work better?

as you guys tell I'm trying to cram some water cooing into a small case, if all else fails I'll just stick to air.
Click to expand...

The rule of thumb is as follows:

If you don't want to overclock:
One 120mm fan slot per water block. So for a two block system with one CPU and one GPU, you'd want an absolute minimum of two 120mm fan slots.

If you want to overclock:
At least TWO 120mm fan slots per block. So, for a single CPU and GPU if you want to overclock, have at least 4 120mm slots in total.

It gets more complicated when you throw in 140mm and other sized radiators, but in general, thicker radiators or stacked radiators buy you very little. It's all about the swept area of the radiators.

Small cases are just silly.

Just grab the biggest goddamned case you can find, and stick it under your desk where it doesn't bother anyone, that way you can get plenty of cooling without needing high speed noisy fans.

When it comes to water cooling (and PC's in general) bigger IS better. :p

I just don't get the SFF trend. I tried it back in 2010, and realized how silly and limiting it was. Since then I've gone big, and will never go back. There is always a lot of space on the floor, under or next to the desk. Extra space just isn't a concern for a desktop.
 
AP2 said:
Thats for confirming guys! I'll give this a shot as I only need to buy a few fittings and a 140mm fan. I'm not overclocking or anything, but this will be for a 8700K and 1080 mini (non ti).

or do you guys think a single 120mm x73mm rad would work better?

as you guys can tell I'm trying to cram some water cooing into a small case, if all else fails I'll just stick to air.
Click to expand...

I think in this case having 2x 140x60's is preferable, since its way more surface area than a single 120x73.
 
Zarathustra[H] said:
The rule of thumb is as follows:

If you don't want to overclock:
One 120mm fan slot per water block. So for a two block system with one CPU and one GPU, you'd want an absolute minimum of two 120mm fan slots.

If you want to overclock:
At least TWO 120mm fan slots per block. So, for a single CPU and GPU if you want to overclock, have at least 4 120mm slots in total.

It gets more complicated when you throw in 140mm and other sized radiators, but in general, thicker radiators or stacked radiators buy you very little. It's all about the swept area of the radiators.

Small cases are just silly.

Just grab the biggest goddamned case you can find, and stick it under your desk where it doesn't bother anyone, that way you can get plenty of cooling without needing high speed noisy fans.

When it comes to water cooling (and PC's in general) bigger IS better. :p

I just don't get the SFF trend. I tried it back in 2010, and realized how silly and limiting it was. Since then I've gone big, and will never go back. There is always a lot of space on the floor, under or next to the desk. Extra space just isn't a concern for a desktop.
Click to expand...

SFF is nice for when you don't want to lug your 100 pound machine around. If you never have to move it and you're not space constrained, then yeah SFF is pointless.
 
Zarathustra[H] said:
How often do you guys move? :p
Click to expand...
It's not just about that though. I think you've seen my little Metis build.

My brother in law is coming into town for Christmas and wants to fire up some lan-party style deathmatch for old time's sake. He and his dad used to play. If all I had were my beastly Evolv, I wouldn't even think about lugging the machine over there to join them. But since I've got that little one handy...

Likewise, I sometimes travel for work. Hotel rooms are a lot less boring with a gaming machine in them.

Sure, it's not as portable as a laptop, but you can still cram a lot more firepower for your dollar into an SFF case than you can buy in a laptop. =D
 
Emission said:
LAN Parties :cool:. They're still a thing, I swear! :geek:
Click to expand...
VanGoghComplex said:
It's not just about that though. I think you've seen my little Metis build.

My brother in law is coming into town for Christmas and wants to fire up some lan-party style deathmatch for old time's sake. He and his dad used to play. If all I had were my beastly Evolv, I wouldn't even think about lugging the machine over there to join them. But since I've got that little one handy...

Likewise, I sometimes travel for work. Hotel rooms are a lot less boring with a gaming machine in them.

Sure, it's not as portable as a laptop, but you can still cram a lot more firepower for your dollar into an SFF case than you can buy in a laptop. =D
Click to expand...

Fair enough.

I haven't attended a LAN party since I could get good broadband at home in ~2002.

I didn't realize people were still doing that.
 
I move my desktop from my house to my GF's/Friends/old work place several times. Each time I wished I had a more compact case. In my GF's case, it isn't as annoying because I'm also karting around my sim racing cockpit. That's a mofo and a half on its own.
 
Zarathustra[H] said:
Fair enough.

I haven't attended a LAN party since I could get good broadband at home in ~2002.

I didn't realize people were still doing that.
Click to expand...

I think there's something to be said for the experience, even if we don't have practical reasons.
 
You may need to put both push/pull fans but it should work, your only long term downside would potentially be noise due to needing to move more air, but it would work. Look at todays modern high horsepower tractors. They put the engine rad, oil cooler, trans cooler, a/c rad, and more stacked on top of each other. If it works for quarter of a million dollar plus machines, it should work for our PC's.
 
jimbob200521 said:
You may need to put both push/pull fans but it should work, your only long term downside would potentially be noise due to needing to move more air, but it would work. Look at todays modern high horsepower tractors. They put the engine rad, oil cooler, trans cooler, a/c rad, and more stacked on top of each other. If it works for quarter of a million dollar plus machines, it should work for our PC's.
Click to expand...
That's not an equivalent system though. The temperature deltas between those liquids and ambient are a couple hundred degrees: so large that even hotter air doesn't lose much efficiency as it's still maintaining a large delta. In PCs, a few degrees in ambient temperature makes a difference in exchanger efficiency, and you'd definitely get that across one rad in a heat soaked system.

Like others have said, it'll work better than a single rad, but worse than two with their own airflow paths.
 
VanGoghComplex said:
That's not an equivalent system though. The temperature deltas between those liquids and ambient are a couple hundred degrees: so large that even hotter air doesn't lose much efficiency as it's still maintaining a large delta. In PCs, a few degrees in ambient temperature makes a difference in exchanger efficiency, and you'd definitely get that across one rad in a heat soaked system.

Like others have said, it'll work better than a single rad, but worse than two with their own airflow paths.
Click to expand...

You're right on, but I think my post came across wrong. My point was supposed to be that given space constraints, it can work but there are barriers. I did fail to mention there are better ways to do it.
 
jimbob200521 said:
You're right on, but I think my post came across wrong. My point was supposed to be that given space constraints, it can work but there are barriers. I did fail to mention there are better ways to do it.
Click to expand...
I'm not convinced that stacked rads wouldn't be worse than a single rad with proper airflow. I don't have the *same* experience, but with my enthoo evolv atx I did notice a big drop in temps moving from a 360 + 240 (with shitty airflow thanks to un-blocked cutouts) to a single 360 (without the unblocked cutouts re-circulating the hot air to the 240).
 
My recommendation is to combine everything into a single loop. Have the flow path go from the exhaust radiator to the intake radiator. This way, the exhaust radiator will always be hotter than the intake radiator, and you will minimize cooling efficiency loss.
 
kumquat said:
Why would it be a bad idea? I think it's at least worth a shot. Cars routinely stack the radiator with the evaporator and it works well. The heat capacity of water is so high I don't think it would make that much of a difference.
Click to expand...
One difference here is the volume of air your evap/radiator stack in a vehicle typically gets. You have a fan, which provides the minimum airflow necessary to keep your systems from overheating. However, as the load on your vehicle increases, so does the airflow (since you are likely moving forward).

Another difference is, sound is not much of a consideration, since it only has to be quiet enough for the sound-dampening and noise-cancelling to be effective inside the cab. You can't make those same concessions in your home office.
 
Tsumi said:
My recommendation is to combine everything into a single loop. Have the flow path go from the exhaust radiator to the intake radiator. This way, the exhaust radiator will always be hotter than the intake radiator, and you will minimize cooling efficiency loss.
Click to expand...


Actually yeah. I forgot today mention that first time around. You ALWAYS want to keep all of your blocks in the same loop. This will always result in lower temps.

Having separate loops with separate pumps is only for show builds. They look cool, but temps are higher than with a combined loop.
 
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