Stacked 120mm AIO Concept

[MEC-777]

I have a Node 304 and I'm considering running two basic 120mm AIO coolers (one for the CPU and one for the GPU with a Kraken G10) stacked with 2 or 3 fans in push-pull exhausting out the back of the case. 

 

Full system specs in sig.

 

Why do I want to do this with a locked i5 and GPU that already has decent cooling? Several reasons;

-Reduce noise

-Reduce temps

-Reduce amount of dust collection on components

 

So the question is; for those that have experience with AIOs and water cooling in general, how well would this work - stacking the rads with the exhaust from one passing through the next? How much heat do the rads typically expel? If I'm gaming for a longer period of time and both the CPU and GPU are working under load, I fear the 2nd rad would become useless. Or would the air passing through be moving fast enough and with enough volume that it wouldn't be an issue?

 

What do you guys think? If you think this could work, which rad would you put as the first? I'm thinking because the GPU usually gets a lot hotter than the CPU during gaming, that it should be placed as the 2nd rad. 

 

 

 

[flibberdipper]

Think of it like this: If you have the CPU's exhaust blowing into the GPU's rad, then the GPU will run at the temp that the CPU is running (like if the CPU is running at 45C, then the GPU will idle at 45C, regardless of it's load). Kind of like a reverse heatsink.

 

At least in my understanding.

[Kukielka]

Very inefficient way of cooling your components, The second rad would just try to cool something with hot air. If only one component is under load the other one might even get warmed up by the warm air.

[MrSuperb]

Think of it like this: If you have the CPU's exhaust blowing into the GPU's rad, then the GPU will run at the temp that the CPU is running (like if the CPU is running at 45C, then the GPU will idle at 45C, regardless of it's load). Kind of like a reverse heatsink.

 

At least in my understanding.

 

nope. the water most likely will never reach 45°C and most likely will always stay below the CPU and GPU temperature.

[flibberdipper]

nope. the water most likely will never reach 45°C

What exactly do you mean by that? Just because it's water, doesn't mean that a CPU won't run at 45C under load.

[Kukielka]

What exactly do you mean by that? Just because it's water, doesn't mean that a CPU won't run at 45C under load.

Water should always be around room-temperature if the cpu get to about 70°C the water wont just grab all the heat at once and stuff it into the radiator.

 

The more water molecules pass by the heatsource, the more heat gets absorbed

 

Physics rox!

[Karumu]

-snip-

 

do you mean like this? 

[MrSuperb]

What exactly do you mean by that? Just because it's water, doesn't mean that a CPU won't run at 45C under load.

 

Let us assume that the CPU is 65°C under load.

The water in the CPU loop might go up to 30°C.

Let us further assume that the GPU doesn't draw any power when ideling.

Then the GPU won't get heat up to more than 30°C by the water.

[flibberdipper]

Water should always be around room-temperature if the cpu get to about 70°C the water wont just grab all the heat at once and stuff it into the radiator.

 

The more water molecules pass by the heatsource, the more heat gets absorbed

 

Physics rox!

Ewww, physics.

[MEC-777]

At idle the CPU usually sits in the high 20's, low 30's (ambient is usually low to mid 20's). Under heavy gaming it goes up around high 40's, low 50's and pushes up to the mid-60's while running benchmarks.

 

The GPU idles the same as the CPU but climbs to the mid-60's during heavy gaming and mid-70's while OCing and running benchmarks. 

 

This is why I think running the CPU as the first rad would be most ideal as it's typically the cooler component by 20-40 degrees.

 

do you mean like this? 

stacked rads.png

Yes, exactly like that. 

[Karumu]

-snip-

it would work better if you were intaking, but i don't think it's a good idea regardless, why dont you have one as intake and one as exhaust

[MEC-777]

Let us assume that the CPU is 65°C under load.

The water in the CPU loop might go up to 30°C.

Let us further assume that the GPU doesn't draw any power when ideling.

Then the GPU won't get heat up to more than 30°C by the water.

This is what I'm thinking. The air exhausting the rads won't be the temp of the components, but quite a lot lower. Thus, it should still provide good cooling for both.

 

I've never used an AIO before so I don't know how much heat is actually exhausted from the rad.

 

Note: these would be basic AIOs like the Corsair H55. Not those thicker rads.

[MEC-777]

it would work better if you were intaking, but i don't think it's a good idea regardless, why dont you have one as intake and one as exhaust

The Node 304 can only support AIO rads mounted at the back as exhaust. The case has two 92mm intake fans at the front and there would be no heat coming from inside the case besides the VRMs on the GPU. So I'm not too concerned with getting cool, fresh air in the case to flow through the rads.

 

The only other way would be to find a 92mm double-wide AIO for the front intake. I haven't looked to see if they even exist... The problem with adding a rad at the front is the storage racks would have to be removed and I'd have to find a new location for the SSD and HDD.

[Faa]

If you don't have any other solution; then do it.

Just make sure you stack the GPU rad on top of the CPU rad with the cpu fan pushing air towards the gpu rad. Lets say you have an ambient of 25°, your water temp will be min 25° but is usually a lil bit higher than the ambient, haswell cpu's don't dump that much heat into the waterloop at all mainly because just google their theory why - so it wouldn't add that much heat to the gpu rad will probably increase it by a few degrees not dramatically. If you do it the other way, eg stacking the cpu on top of the gpu rad, your cpu temp will raise drastically.

[MrSuperb]

-Reduce noise

 

if your aim is to reduce noise, don't use 120/140mm AIO wc solutions ...

[MEC-777]

If you don't have any other solution; then do it.

Just make sure you stack the GPU rad on top of the CPU rad with the cpu fan pushing air towards the gpu rad. Lets say you have an ambient of 25°, your water temp will be min 25° but is usually a lil bit higher than the ambient, haswell cpu's don't dump that much heat into the waterloop at all mainly because just google their theory why - so it wouldn't add that much heat to the gpu rad will probably increase it by a few degrees not dramatically. If you do it the other way, eg stacking the cpu on top of the gpu rad, your cpu temp will raise drastically.

That's what I'm thinking - in this order: intake-->CPU rad-->fan-->GPU rad-->fan-->exhaust (--> being the direction of air flow). If water temps are only in the 30's, then this shouldn't be a problem as long as the air is moving through at a decent rate. The Node 304 has a built-in 3-speed case fan controller, so I can play around with that and see how that effects temps. 

 

Yeah, apparently Haswell's have poor heat transfer due to crappy thermal paste between the chip and the lid or something like that, thus they run a little hotter in general. That's ok as mine is a locked i5 and temps are pretty good, even with the stock cooler anyways. 

[Faa]

That's what I'm thinking - in this order: intake-->CPU rad-->fan-->GPU rad-->fan-->exhaust (--> being the direction of air flow). If water temps are only in the 30's, then this shouldn't be a problem as long as the air is moving through at a decent rate. The Node 304 has a built-in 3-speed case fan controller, so I can play around with that and see how that effects temps. 

 

Yeah, apparently Haswell's have poor heat transfer due to crappy thermal paste between the chip and the lid or something like that, thus they run a little hotter in general. That's ok as mine is a locked i5 and temps are pretty good, even with the stock cooler anyways. 

And because they have a poor heat transfer there's not much difference between the cpu coolers watertemp & ambient so it would barely effect your gpu. I doubt it would make a 5° difference. The cpu would blow 30° of air and the gpu might sit at 45-50° and 30° air is better than nothing.

[MEC-777]

if your aim is to reduce noise, don't use 120/140mm AIO wc solutions ...

Have you heard the 3 fans on these windforce cards at full-bore? Not deafening, but not quiet either.

 

The stock Intel cooler can make a surprising amount of noise on it's own too. 

 

Reduced noise would be an added bonus at the least, but it's not the main focus behind this. The main reasons are reduced dust build up and cooler temps.

[Lays]

Let us assume that the CPU is 65°C under load.

The water in the CPU loop might go up to 30°C.

Let us further assume that the GPU doesn't draw any power when ideling.

Then the GPU won't get heat up to more than 30°C by the water.

 

 

In my experience in my own loop, the water was usually ~10-13c lower than my GPU's.  I got bored one night and stuck temperature sensors in my reservoir after a few hours of gaming to see hot hot it was.

 

When I tested, the GPU's were 55c with the fans at 600 RPM, and the water was 42-44c, this may vary depending on fan speeds, obviously if fans are slower, more time is left for heat to build up inside the loop.

[MEC-777]

Alrighty, so I picked up a Corsair H60 to use just on the CPU for the time being (and continue running the stock GPU cooler). In a few weeks I'll add in an H55 for the GPU and see how it all works. It's going to be a very crowded case, that's for sure. There's room for both rads but the hoses don't have much flex to them. Still amazed how much you can fit in to such a small case.

[Bagmup]

How are you going to physically mount the second radiator? Double sided tape? The bolt mounting holes don't go straight through the rad.

[MEC-777]

How are you going to physically mount the second radiator? Double sided tape? The bolt mounting holes don't go straight through the rad.

I'm working on that. Have a couple ideas.

 

 

***

Got the H60 installed on the CPU this evening. Wow! -20 degrees cooler under full load and it's dead-silent! I love it!

 

The air exhausting the rad even at full load (fan only needs to run at 1200rpm) is still cool - very close to ambient temps. So I think this will work just fine with the rad for the GPU mounted behind it.

 

Completely re-did all the cable management since I had to remove the motherboard anyways to mount the cooler bracket. I think I did a pretty good job considering it's a non-modular PSU. Pics coming soon...

[MEC-777]

Alright, here it is. Two AIO's in one Node 304.

 

The 304 has these screws for mounting HDD's to the drive bay brackets. Since I'm only using one bracket, I had lots of extras kicking around and they happen to be the perfect fit to go inside the mounting brackets on the center fan to fasten to one rad on both sides.

 

Test fitting...

 

Tight squeeze. It "touches" the H60 block on the CPU but is not pressing against it. 

 

USB 3.0 cable still fits with careful routing.

 

Working on the GPU...

 

Gigabyte already installed a very nice VRM heatsink which sits perfectly just below the fan on the G10 bracket.

 

Back in the box...

 

Had to mount the block and bracket on the GPU with the card installed in the case due to constraints on space, rad and hose position...

 

End results:

 

It's alive!

 

 

Did my best with cable management, given the circumstances.

 

Ok, temps... On average I'm getting about ~20* cooler on the GPU and CPU while gaming with the 3 rad fans on low (about 800-1000rpm). Running Crysis 3 for about 30-45 mins with the GPU overclocked, same results but I had to bump the fan up to medium (about 1200-1400rpm) and it was still whisper-quiet! In case anyone asks, I tested with the cover on.

 

The CPU rad remains cool to the touch while the GPU rad actually gets quite warm. This is exactly what I expected and thus far, it's performing perfectly. If you wanted to run 2 GPU rads like this, I would not advise it because GPU's get much hotter than CPU's and there's quite a bit of warm air being pumped out the back - the 2nd rad in line would just boil (literally). In this instance, both rad are receiving cool air and thus, it works. 

 

The 92mm fan over the VRM works really well at both cooling the VRMs and pulling more cool air in the case. Surprisingly, even when being taxed, that fan does not thrown off any heat from the VRMs, so temps inside the case are FAR lower than before. With three 92mm fans, total, pulling in fresh air and very little to no heat being radiated from inside, the two rads are easily kept fed with fresh, moving air.