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So I got condensation in my PC for the first time today :P

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So basically winter caught me off guard and I woke up to this:

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I am using external watercooling with MO-RA3 placed in a different room on the attic that is not actively heated. Tonight, the temperature outside went down to -5C suddenly, which caused that room to cool down to like 5C.

Normally that wasn't the problem, because my entire system was watercooled and it was dumping all its 500-1000W heat into that room, so it was never really going down below like 8-10C, and ambient inside the case was roughly the same as my room ambient, around 18C/40%RH, even with panels closed because some slight radiation from blocks and tubes was the only heat source there, so dew point remained around 5C. I was using this setup already for 2 years with 6900K/2080Ti SLI system and it was always within safe margins.

Right now though, I do not have the block for 4090 yet so not only I am not dumping any real heat into radiator room, but the GPU is heating up the case ambient even at idle and with side panels open, so the ambient in radiator room went down to 5C, and case ambient went up to 25C, resulting in dew point around 11C, so water was whole 6C below dew point. And of course, I fell asleep yesterday, so PC was idling like that the entire night :p

Fortunately, it is all jerry rigged together randomly before I get the block so I kept paper towel on the GPU backplate. After closely inspecting the case and the paper towel though, there were no droplets that actually dripped down, which is pretty good considering that it was left like that for hours and water temperature was 6C below dew point. Also, the CPU block was perfectly fine with no signs of condensation, so I guess the ~25W that the CPU draws idle was enough to keep it warm.

Very interesting start of the day :p It is a pretty good experience though, 6C below dew point with air cooled card dumping some hot air into the case, even if idle, sounds like it should be an absolute disaster, and it wasn't that bad really. It took forever for condensation to form, and it still didn't drip, although it was quite close. With all watercooled parts and insulated tubes you can probably run below dew point just fine, GPU and CPU blocks have enough of their own heat even at idle to stay warm, only parts that do not are a problem it seems.
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Discussion Starter · #5 · (Edited)
It sounds like the issue was leaving the MO-RA in that unheated attic. Which means it's bound to get worse as outside temps stay subzero for extended periods of time.

You should look into insulating the tubing that travels to the MO-RA if you want to be safe over the long term.
As I explained already in the main post, things do balance themselves out assuming everything is watercooled and dumping heat into that attic room. I was using this setup for 2 years already with 6900K/2080Ti SLI and everything was always within safe margins, the room was never below 8-10C and dew point inside the case was below 5C because the main room is temperature and humidity controlled with AC and there were no major heat sources within the case. But now the temporary situation is that I do not have GPU waterblock yet, so not only I am not heating the attic room up with GPU heat, but heating up main room instead, so everything went completely out of balance. It will be fine once the GPU block is in, temp within the case will go back to 19-21C, so dew point will go back to 5-7C, and attic room temp will go back to ~8-10C at the worst, so water will be like 11C idle.

Even in the worst case scenario like this one I was only a few degrees off, just lowering the case temp by 2C and increasing attic temp by 2C would avoid the problem.

Having it like this during winter is great as it is basically a free water chiller, but one condition is that the heat from PC has to be dumped into radiator room to maintain good temperatures there, which cannot be done without GPU block. I have to wait till 22/12 for delivery so I will have to actively heat that room up temporarily.
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Discussion Starter · #7 · (Edited)
^ That only works assuming your temp in the attic stays at a constant temperature or doesn’t drop further.

Assuming you live in Poland, I know most residential houses don’t insulate the roof. Rather it’s the ceiling plane beneath the bottom of the roof trusses or beams. Or in other words - the attic is unconditioned.

It can get also get quite cold in the winter. Not as frequent or drastic as Canada… but I’ve spent a lot of time in małopolska, and it does drop to negative temps frequently in the winter.

As long as you’re confident a constant 400-500w being exhausted by your radiator will maintain a decent temp in your attic, you’re OK. An idle system will keep blocks warm, sure… but your loop temp could still be below dew point on very cold days and you still risk condensation.

I also still think you’re underestimating how the air cooled 4090 is influencing behaviour in your case. Dew point isn’t just based on ambient temp.

I would advise reconsidering the location of the rad or at least insulation. Even a semi-enclosed enclosure around the rad to mitigate some of the cold is an option.

The risk for a short is high given the volume of most attics and the unknown temperatures of an unconditioned attic in the winter.
Well, I am actually a roofer, and I have the roof insulated because I live there. It is divided in 3 rooms, one is my room which is under AC and very insulated both thermally and acoustically, one is corridor, and one is this attic room. It is like a 3x3 room with reclined celling from the roof so the actual volume is more like 2x2 room, it is not hard to maintain temperature there, there just need be some heat source, which there isn't right now, and I had a roof window slightly open because this room also serves as a mini gym you could say.

Also for the summer I have it configured so that the rad is pushing hot air to the outside through the wall, and I still haven't disconnected that, so whatever little heat I was producing from CPU benching and etc was going to the outside. It is just the weather was unusually good this year and I was caught off guard by the sudden temperature drop. There was also first snow today and there is already 6-8cm thick snow everywhere, it is just insane change of weather in just one day. Combined with the fact that I don't have GPU block yet, it was like the worst combination of circumstances possible. And even with all of that it was still only slightly off by few degrees. I am confident it will be fine once the loop is complete.
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Discussion Starter · #9 · (Edited)
Ah - you’ve should of clarified from the start it was a conditioned space! This my frame of reference: View attachment 2583820

Look - my posts were just to flag the risks and seems like you’re on top of it. Just don’t want to see you fry your hardware :)
My main room is conditioned, radiator room isn't, but it is insulated, not very well and roof window is very old and not good, but still :p

I get what you mean, I didn't take your post as an offence, your points are correct and this whole situation here has a pretty tight margins, so is understandable that it would raise concerns. I certainly wouldn't recommend something like this unless someone really knows what he is doing and has sensors monitored at all times, and even then, one mistake or combination of bad circumstances, like what happened with me today, could be lethal.

Looking at how long it took the condensation to form and how it still didn't drip despite sitting like this for ~10 hours with water temp 6C below dew point I think the mistake would have to be very big to cause some serious damage, so it is not like you go one degree below dew point and everything explodes and it is not easy to do something like this in the first place, this is a very unusual situation, but still.
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Discussion Starter · #19 ·
Nah, just need to throw more heat in there and things will be great! Curious as to what OP does in the summer, however. With the temperature swings we have in the states, there is no way that would fly here.We can go from -11 to +38C from winter to summer in a NORMAL season in the northeast.
There are similar swings here from around -15C to +40C, only those extreme values are only for a few days a year and may not happen at all, it generally stays in -5C to like 35C range, and it is not uncommon to have winters with barely any negative temperatures, although not this year it seems :p

In the summer I still keep the rad where it is, but I made a vent through the wall so radiator can throw heat to the outside through 200mm channel, because heating up already fairly hot room with PC heat could result in 40C water temps at times. There are still cases of ~35C water temp during worst days, which is not optimal, but it is not dangerous in any way, so it just annoyance. On my X99 setup I had to dial things down a notch for some hotter summer days, here I have enough headroom that I don't think I will have to.

What a risky setup. I keep my whole system air cooled cause liquids scare me lol. I'm not breaking any 3DMark records, but i can sleep alittle more easy at night.
I thought that at the beginning too, like many people did for sure, but once you do it, it is not so bad. A lot of this is down to configuration, component choice and it is quite heavy on manual skills, but if do everything carefully then the chance of leak, especially catastrophic leak, is not much higher than your PC just randomly dying on you. Sure, form over function hard tube with gunk fluid and all components inside the case kind of setup has a much higher chance of issues, but soft tube distilled water based external watercooling setup has minimal leak points inside the case and is basically maintenance free.

And even if you really screw something up, even with soft tubing somehow, it is not like you are going to have geysers of water in your case, it will be a droplet of water every now and then, and even that can be prevented by having negative pressure inside the loop, so water is sucked back in.
And even if you do get something wet, it doesn't necessarily mean it will die instantly. I think Jay did a test like that in the past where he just sprayed water on the backplate of running GPU, and it took a long time before anything happened, and it was Displayport that gave in in the end and not the GPU itself if I recall correctly.

So it is not all that scary as it seems, you can do damage even with basic things like for example not sitting you CPU correctly and destroying the pins, or not plugging your 12VHPWR cable all the way, a very easy mistakes to do by anyone and they do not involve any water. It is important to be careful and thorough, but also not to be paranoid.


You need a waterchiller. it’s so easy to stay above the dew point and never ever get condensation on your hardware. Unless you want condensation lol.

I can just set a 13C-14C water temp year around. And never ever worry with it. You can go a little cooler in the winter though if you like. And if you want to bench or keep it even colder, just properly prep your motherboard for the condensation. And run the water at 3C. It’s so easy and reliable!

I run a chiller 24/7. I don’t even need my enormous external radiator anymore.

View attachment 2583906

View attachment 2583907
I actually considered that in the past but went with MORA instead. I might still do it, having the same temperature year-round sounds great. Now that I have dropped my power draw massively by going from 6900K/2080TiSLI to 13900K/4090, especially idle draw is halved and went down by like 125W, power wouldn't even be that much of a concern anymore.

Question is how much power I need. 1/4HP one like the like one you are using would draw like 190W, so that is nothing, but is it enough for both CPU and GPU? Probably not. According to stats I would need 1/2HP one which draws 375W, and that is quite a lot. It probably won't run all the time though.

Are you using it with normal D5 watercooling pump?

One idea I also had with this, I don't know if you considered it, would be to have some 360 radiator with low RPM fans at the intake of the case that would receive cold water together with the rest of the loop and cool case ambient a bit. I think it should drop case temp by like 5C and improve dew point quite a lot but still wouldn't be powerful enough to cause condensation on the case.
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