New Custom Loop using external Radiators & Fans

Chinez

Chinez

Chinez

Associate
Joined
27 Aug 2025
Posts
4
Location
UK LONDON
Hi Overclockers UK,


I am looking to build a custom water cooling loop for my existing PC, which includes the following components:

  • MSI X870E Carbon WiFi
  • Gainward Phantom 5090
  • Delidded 7950X3D

I'm currently renovating an external outhouse, and due to the heat generated by my PC, I'm interested in setting up a complete custom loop. However, I'd like to utilize external radiators mounted outside and cladded over for discretion.

A few questions:
  • What fans would be best suited for this setup?
  • What radiators have people used successfully in similar external configurations?
  • Will I need extra pumps to handle the longer runs?

I'm considering using insulated copper pipework for the outdoor sections, then switching to quick connects once inside the property.


Additionally, would it be possible to use antifreeze in the coolant? If so, do you have any recommendations for types or mixtures that others have used effectively?


To combat condensation during the winter months, I'm thinking of incorporating some form of pipe heating system to slightly raise the pipe temperature and reduce moisture buildup.


Any help, advice, or recommendations would be greatly appreciated!
 
What fans?
Shouldn't really matter as long as the wiring
Isn't exposed to the elements

What radiator ?
Mo-ra very expensive
Alphacool much cheaper
DIY option use a car radiator

Pumps
Yes wouldn't just use one pump
Minimum of 2 depending on how long
The tube runs are maybe 3
Plus gives redundancy if a pump fails

Antifreeze?
Yes you absolutely can put Antifreeze in
The coolant
Recently put some in mine
As had no biocide or anti corrosion stuff handy
What ratio water to Antifreeze you would have
To Google for someone who has done it
I only used a little as not external radiator

Condensation
Not actually sure it's an issue
Pretty sure one of the guys in here put
His radiator outside in Scottish winter
But had no Condensation issues
Got a bad memory but will tag who I think
It is to see if they can answer that part
@pastymuncher

Apologies if that's not who it was
 
They weren't outside but fitted in a radiator box on a windowsill sucking outside air through them. I wouldn't put them outside, especially up here as we can be below zero for weeks and they would freeze. This gave me ultra low temps in the winter even with the window only opened a crack. I got down to 4-5 degrees C water temp and did not have any condensation in the pc at all. It was amazing playing a demanding game yet only having cpu and gpu temps in the low 20's with all fans running at a silent 750rpm. I had a pair of Hardware Labs Black Ice GTX280 rads with 8x Arctic P14's fitted to them in push/pull with Mayhems X1 as the coolant. Pumps were a pair of Alphacool VP655's (D5 Vario's) because I had a tubing run of around 15m made up of a mix of 12mm copper pipe, Mayhems 12/16mm ultra clear soft tubing and 14mm Monsoon hardline tubing inside the case. In the end I packed it in after over 17 years of watercooling for a number of reasons. It was getting stupidly expensive back then and has only got even more ridiculously expensive now, hardline tubing was a pain when I needed to swap anything in the pc out and I realised I could have perfectly acceptable temps going back to air cooling without spending a fortune on overpriced coolers.

I bought a Thermalright Peerless Assassin SE120 ARGB for the cpu (a i5 12600 non k at first then my 7800x3d) and stuck a third fan on it and set all fans to run on my motherboards silent profile and temps were maxxing out in the 60's. I originally had a Gigabyte RTX 3070 Vision OC which was under water cooling so that had it's stock cooler fitted which turned out to be very good especially after I refitted it with Gelid Extreme pads and Thermal Grizzly Kryonaut on the core. I was running out of vram with that card on a couple of games at 1440p sao swapped to the 7900GRE I have now. Foolishly I tried improving cooling performance on it by changing pads and a phase change pad on the core and fell down the rabbit hole of chasing temps. I changed things on this card 6 times before I was happy and it turned out that Asrock use high quality pads and paste straight from the factory!!
 
@pastymuncher Thank you for the feedback , I only just see that there was reply on this thread as its quite a unusual thing to do.
So to me this all sounds great , I think I'm going to use cooper pipe to go through the walls and then use plastic for the build.

Also the idea of using a small box mounted on the external wall (to deflect rain and harsh weather sounds like a plan).

I will keep this thread updated as I make the build ;)
 
Chinez said:
@pastymuncher Thank you for the feedback , I only just see that there was reply on this thread as its quite a unusual thing to do.
So to me this all sounds great , I think I'm going to use cooper pipe to go through the walls and then use plastic for the build.

Also the idea of using a small box mounted on the external wall (to deflect rain and harsh weather sounds like a plan).

I will keep this thread updated as I make the build ;)
Click to expand...
@Mcnumpty2323 I take it with the pump locations I would have to do 1 pushing it out the wall and then 1 pushing it back in?

Sorry I have never ever done a custom watercool loop before :eek:
 
Would this be a effective loop , or would it be best to keep them separate?

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At least i got the right person
Even if i got the details a little bit wrong

Assuming one loop for both cpu and gpu (pumps in series)
Pump location i would go for wherever
Is most convenient to be able to power them
Or replace if one ever failed
Multiple pumps in series increases head (pressure basically)

Doesn't really matter if they are next to each other or not
On the scale we are talking about
Yeah if it was an industrial pipe miles long they might use spaced out
Pumping stations
But can't see it being necessary for pc watercooling
 
Chinez said:
Would this be a effective loop , or would it be best to keep them separate?

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Click to expand...
There's arguments for both approaches
2 loops one for cpu and one for gpu
I prefer 1 loop as long as you have enough pumps for redundancy
If do 2 loops and want redundancy you need 4 pumps then

Redundancy =no downtime to me
Or more accurately i guess it would mean
You can delay the downtime until it's not when you
Urgently need to use the pc

If going to all this trouble
I would probably go for an Alphacool 1080mm x 45mm radiator
Rather than individual radiators
A ocuk competitor does stock those
But can't link a competitor in here
Think they order them from Germany on demand
As not something that sells in large volumes
 
I had both my pumps one after the other as it was much easier for the wiring and plumbing, I had everything in a single loop. I also had a big inline filter before the pumps just in case and it paid off despite cleaning the rads out thoroughly. Still not sure I would put the rads outside though.
 
To be honest nowadays
Custom watercooling is expensive
And doesn't provide as much advantage as it used to
Modern cpus can be handled with a thermalright air cooler
Very cheaply
Gpu can put out a lot more heat but usually have
A hefty heatsink on them that can cope with it

Cpu single core overclocking doesn't give a 50% boost
Like the old 2600k days anymore
And Undervolting gpus is usually the way to go now

That leaves getting the heat out of the room
On this point I actually agree with putting the radiator outside
Or on a windowsill at Very least
But theres the question of where you are to consider too
Pastymuncher is up north
You are in London
I am across from France near enough
The difference in weather/temperature variation between those 3
Is pretty big
Some antifreeze In the coolant and I would be pretty confident
It wouldn't freeze in winter here whereas in Scotland
It would get much colder
That's why I moved south lol
Now it gets too hot here
But on the plus side only seen serious snow once down here once
in 30 years this little corner usually avoids it
and they grow cauliflowers in the winter

right now here it's 21c outside
Was 24c in pc room when I turned on the pc
It's now 30c in the pc room and it's September
It was much higher in here in the summer

Given the option
Self installing air con would probably be my choice
If it was practical
My stepson did his himself for about £500 then had it signed off
By air con engineer
That's comparable to setting up a custom loop nowadays
I priced up an Alphacool 1080mm radiator
And the bits and pieces I would need to put the pc on the windowsill
Came to £400 and that's a simple move it a few feet
Not put it in another room/ouside

Edit
And i chose bits and pieces that weren't aesthetically matching
To keep the price down
Making it aesthetically pleasing would cost more
 
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You're basically gambling that whatever antifreeze mix you put in is able to cope with what you consider to be the lowest outside temps you think you will ever get where you live. So, you've got to decide on a water/anti-freeze mix ratio based on what you think will be the lowest ever temperature. Then cross your fingers it will never go below this temperature ever. And if it does ever go below that temperature then the ice expansion will very probably completely bugger up your external rad. So it fundamentally depends on getting your sums right on the mix, and then hoping that also covers the once in a decade "beast from the east" winters we can get.

If I was ever going to do this I would have the pipework and rad mounting setup such that I could bring it in at night. But I know I could never be arsed to do anything like that, so I would rule it out on that basis, since I personally don't want to be gambling getting the antifreeze mix right, cos if it expanding ice did destroy the rad you probably wouldn't know until the next day when it thaws and pumps out all your coolant down the side of your wall, and then you'd have to spend days trying to fix it in the middle of winter.
 
I agree mostly with what Mr Mcnumpty says, water cooling is now stupidly expensive and apart from looks is largely a complete waste of time and money. I gave it up around three years ago due to increasing costs and the hassle of it all plus I realised that a £30 Thermalright dual tower cooler could more or less do the same thing. No, the temps were not stupidly low like when I had water cooling but they were not high either. In addition I always buy a gpu that has a very good cooler and the Gigabyte 3070 I had at the time was no exception. Once the cooler was refitted with decent pads and thermal paste it ran very cool and very quiet and with the cpu cooler using my motherboards silent profile for the fans I more or less had a silent pc that ran very cool. I have got a Thermalright AIO on the cpu now but that was due to problems with my previous case and a obsession with chasing gpu temps that ended up with the cpu cooler suffering from heat soak from the gpu otherwise I would still be on the Peerless Assassin. Would I ever go back to full custom watercooling again? Not a chance!!
 
Yeah it's not like the old days anymore
Aesthetics wasn't really of any concern back then
Aquarium pumps,diy plumbing stuff
Anything that did the job basically we used it

But now Aesthetics means large price hikes
Due to glass panel pc cases meaning everything is
On show

And the gains over aircooling are pretty much null and void
Getting the heat out the room is getting
To be a priority instead
 
I would be a little concerned about how effective it will be outside, if you intend to put it under cladding then how would fans be effective? It would radiate heat under there and essentially it’s not really cooling at that point or to put it another way it’s not cooling better than just putting it in the case.

If the issue is heat inside the outbuilding then why not deal with that issue instead? Or the radiator inside but able to expel hot air out, like your bathroom vents. AC install in the room is almost certainly less effort and cheaper I would wager.

Not to discourage an interesting project but I think it’s going to be really complicated and full of annoying issues that pop up.
 
Would depend how they clad it/box it in
You're trying to keep rain off the fans /wiring
Though I would probably seal wiring with silicone too
Doesn't mean it has to be
A fully enclosed box Though
Start off with boxing 3 sides then use Angled overhangs
With a gap to let heat out/prevent rain ingress

But yeah I already said
If its practical shove air con in the room instead
Basic plumbing / diy skills needed
My stepson had never done it before but pretty similar idea
To a watercooling loop
And he found a forum specifically dedicated to installing
Your own air con which gave him a list of everything required
and a guide how to do it
He put it in then leak tested it
Then had it signed off By an engineer (for insurance reasons)who also
Leak tested it etc
 
Another problem I have thought of with sticking the rads outdoors is beasties. Unless you use some sort of filtration the rads elements will be full of dead flies and be home to several spiders and their webs. It's just too much hassle to make any sense.
 
That's a reasonable point
Not sure how bad it might actually get

Could just use a pair of tights as a filter
Cheap and pretty effective
If i remember correctly one of our ocuk forum members
Did a video about that
Youtube channel hands on Katie
 
Do bugs and debris really matter that much on an external rad? Quite trivial to strip fans off rad and clean with compressed air/brush.

Plenty of applications use similar systems. Heat Pumps, A/C, Car radiators etc.
 
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