What max coolant temp should I be targeting?

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Thunderdolt

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I'm configuring my alarms to trigger on high coolant temp, but am not sure how high to set that limit. Is something like 40C a normal temp to see, or is that in the "oh sh!t" warning range?
 
Thunderdolt said:
I'm configuring my alarms to trigger on high coolant temp, but am not sure how high to set that limit. Is something like 40C a normal temp to see, or is that in the "oh sh!t" warning range?
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I usually target a coolant temp of between 31 and 33C with my fan controls. This is just because I like to have my GPU run at 40C or lower for max boost clocks, and this usually accomplishes that for me, but YMMV based on components and configuration.

As far as the greatest temp that is safe? I think D5 pumps are rated for operation up to 50C water temps. I remember reading this somewhere, but I cant find it right now.

40C should probably be a more typical max coolant temp. I consider 50C a little high, as it might have negative effects on the loop particularly around fitting seals. 40C is probably more normal. My low 30's are probably a bit extreme.
 
40C is the default setting for the audible alarm on the D5 Next. Found that out by accident last night :) Maybe I should stick to that as my guide for now.

This is interesting. I may have to rip out these ML120s and replace with something higher flow. I'm surprised that this setup can't quite keep up with the CPU. On this loop, the 300W CPU is the only heat source and the radiator is 360x60mm with ML120s in push-pull. CPU is currently holding 84C with coolant at 41C.

This also means that the GPU loops may be insufficient given that they have ~600W to dissipate and are only 480x60mm with ML120s in push-pull.
 
I tend to work and set up the machines to a max of 10C delta over ambient temp... usually 10C - 15C delta over ambient is considered normal.. I usually work with deltas as is not the same an ambient temp of 18C and a coolant temp of 35C as an ambient temp of 25C and a coolant temp of 35C..
 
Araxie said:
I tend to work and set up the machines to a max of 10C delta over ambient temp... usually 10C - 15C delta over ambient is considered normal.. I usually work with deltas as is not the same an ambient temp of 18C and a coolant temp of 35C as an ambient temp of 25C and a coolant temp of 35C..
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I tend to work on absolute coolant temps, as deltas allow too much variability in the final resultant core temps. I want to keep that fixed, and let the fans adjust if it gets warmer.
 
Thunderdolt said:
This is interesting. I may have to rip out these ML120s and replace with something higher flow. I'm surprised that this setup can't quite keep up with the CPU. On this loop, the 300W CPU is the only heat source and the radiator is 360x60mm with ML120s in push-pull. CPU is currently holding 84C with coolant at 41C.

This also means that the GPU loops may be insufficient given that they have ~600W to dissipate and are only 480x60mm with ML120s in push-pull.
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Even a slim radiator with three ML120s in push should be able to handle that CPU with no issues. Here is an example of a 360x30mm radiator cooling something in the neighborhood of 400W (550W at the wall) and keeping the coolant temps below 40C with the fans running at just 800 RPM, and the ML120s push more air at the same RPM than the ones used in that review. You need to be looking for issues elsewhere in the loop.
 
Thunderdolt said:
I'm configuring my alarms to trigger on high coolant temp, but am not sure how high to set that limit. Is something like 40C a normal temp to see, or is that in the "oh sh!t" warning range?
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Generally you do it by delta. First you gotta figure out your starting point, ie. loop running idle for x minutes. Fyi, radiators are measured in delta of water temp. Ideally we keep the water delta within 10 degrees of baseline. And on the matter of water temp, your pump if its PWM should use water temp as its sensor. Here's an example of a loop using water temps to control fans and pump. The other positive with using water temp sensor for fans/pumps is that water temp can monitor both cpu and gpu loads. If you monitor cpu temp alone, the gpu can get real hot while the cpu sits idle and vice versa.

Thunderdolt said:
This is interesting. I may have to rip out these ML120s and replace with something higher flow. I'm surprised that this setup can't quite keep up with the CPU. On this loop, the 300W CPU is the only heat source and the radiator is 360x60mm with ML120s in push-pull. CPU is currently holding 84C with coolant at 41C.

This also means that the GPU loops may be insufficient given that they have ~600W to dissipate and are only 480x60mm with ML120s in push-pull.
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You need more radiator. What components are in this equation btw?
 
I would do it this way:

See what the delta T is between your CPU and water temp. Determine what maximum CPU temp you would be comfortable with. Set your target coolant temp based on that.
 
Tsumi said:
I would do it this way:

See what the delta T is between your CPU and water temp. Determine what maximum CPU temp you would be comfortable with. Set your target coolant temp based on that.
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Exactly. If overclocking, take it one step further.

1.) Achieve maximum overclock with max cooling
2.) Back off cooling. Note at which CPU temp you start seeing instability (or lower boost)
3.) Note delta T between loop and coolant.
4.) Set target temperature on loop as target chip temperature minus delta. Add a safety margin if you feel like it to account for load variation.
5.) Set alarms (if you really feel you need them) a few degrees higher than temperature set points, so they only kick in if something is going wrong.

This is what I do for my GPU.

I set the fans to control loop temp using my Aquaero's set point controller (works much better than fan curves at keeping fans quiet. Fan curves by design always run the fans faster than they need to)

I used to set them to 35C, because I found that a 5C gap was all I needed to keep my GPU below 40C, and if it is below 40C at load overclocked, it always reaches the max possible boost.

I have since revised it down a bit. 32 to 33C I think it was last (but my settings got wiped recently when I did a clean Aquaero install)

Two things resulted in this change. One was that I came across titles that ran hotter than I was used to, and the other was that I got a Gsync Compatible screen, so I was no longer using Vsync to throttle the GPU, and thus it had to work harder.

The CPU I don't care about. I've concluded that it is pretty much pointless to try to overclock the Threadripper, so anything I do to keep the temps OK for the GPU are going to be enough for the CPU, even at full load.
 
By design of GPUs and GPU waterblocks, the delta between GPU core and the water is usually less than that of CPUs. GPUs tend to have higher maximum temperatures than the CPU, so keeping the CPU from throttling IMO is a better target than keeping the GPU at a low temp. Not sure if modern GPUs have instability at lower temperatures these days, I'm still currently on a GTX 690.
 
Thread necro...

I have a 5900x & 3090 FE on a single 420MM rad, water temps while keeping noise reasonable are about 45c.

Is that an OK Temp? If not it looks like I'm getting a new case and another Rad :)
 
Digital Viper-X- said:
Thread necro...

I have a 5900x & 3090 FE on a single 420MM rad, water temps while keeping noise reasonable are about 45c.

Is that an OK Temp? If not it looks like I'm getting a new case and another Rad :)
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I mean....I guess a long as your components are at a fine temp it's okay. Personally, assuming you're at a normal room temp, that sort of temp delta is way too high for me.
 
I wouldn't say ridiculously high, but high enough that adding a rad, or going for a thicker rad may be a good idea.

However if you are running PETG hard tubing it can start to deform when coolant stays above 40c or so.
 
Digital Viper-X- said:
Thread necro...

I have a 5900x & 3090 FE on a single 420MM rad, water temps while keeping noise reasonable are about 45c.

Is that an OK Temp? If not it looks like I'm getting a new case and another Rad :)
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Define OK. Are you getting performance throttling? Do you prefer your CPU and/or GPU load temperatures to be lower? Do you want to overclock higher, but can't because of thermals? If yes to any of those, it is not OK. If the answers are all no, then I don't see any point in spending additional money for something that will net you no tangible benefits.

If you want a reason to tear your computer apart and modify/expand it further... then the question isn't whether or not your temps are okay, it's how much satisfaction you will get out of working on your computer vs the cost put into upgrading it.
 
Tsumi said:
Define OK. Are you getting performance throttling? Do you prefer your CPU and/or GPU load temperatures to be lower? Do you want to overclock higher, but can't because of thermals? If yes to any of those, it is not OK. If the answers are all no, then I don't see any point in spending additional money for something that will net you no tangible benefits.

If you want a reason to tear your computer apart and modify/expand it further... then the question isn't whether or not your temps are okay, it's how much satisfaction you will get out of working on your computer vs the cost put into upgrading it.
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I'm more worried about the pump dying to high temps :) (also noise) I already ordered a new case and 2 x 360 rads... this was a newish build, but I used my old Core P3 to build it in, which is limited to a single rad unless I use some 3d printed rad mounts. (at this point it looks a bit odd, and takes a way from the finish)

20210101_155456.jpg
 
Your pump won't die from 45 C water temps. If it was hitting 75 C then you can worry about pump life.
 
60c is max water temp for both DDC and D5, so you're getting closer to that limit. It's not a limit I EVER want to get close to. If you were on DDC, the pump electrics would probably equate to 95c. On D5, not so bad since its dumped into loop, but really at 45c water temp you're not doing much cooling.
 
Loop component health won't be compromised at 45°C, but you do kind of want to maintain a healthy safety margin to the 50-60°C where problems start to arise.

45°C would make me a little uneasy personally.

There is also the matter of what you are trying to accomplish.

These days a water loop generally has the biggest impact on GPU temps, dropping them significantly over stock coolers.

I find in most titles I can maintain an overclocked core temp at max load on my Pascal Titan of 38°C when my loop temp is 32°C, but that requires good flow. I find that generally my GPU core temps at load sit at between 4°C and 6°C above loop temp with good flow, depending on the title. (newer titles have tended towards the 6°C, with slightly older ones at 4°C, not sure what has changed in the render pipeline over the last several years to result in this) This may seem as total overkill, but I ahve actually found that at least for the Pascal Titan, a 40°C core temp seems to be the magic number above which my boost clocks start to drop.

So, from that perspective, even with a 45°C loop, you should see GPU temps significantly below that of the stock air cooler.

The tricky part is the CPU. For whatever reason, I have found the benefits from a water loop to be much smaller when it comes to the CPU. This has been across several mounts with two different CPU blocks in the last 5 years. If you are looking for much improved CPU temps, this is where you really want a lower loop temp.

At some point, if you are letting your loop temp get up there, you have to ask yourself why you are bothering with a custom loop, if you aren't going to see much of a temperature improvement.

I tend to target 31°C to 32°C, but everyone has their number for their loop they are comfortable with.
 
I think a number is what, 40C if you are using PETG tubing? Higher and it can deform. I know some vendors sell little plastic inserts to put at the ends of tubes to keep the rigidity if it does happen?
 
Zarathustra[H] said:
The tricky part is the CPU. For whatever reason, I have found the benefits from a water loop to be much smaller when it comes to the CPU. This has been across several mounts with two different CPU blocks in the last 5 years. If you are looking for much improved CPU temps, this is where you really want a lower loop temp.
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its the use of IHSs causing that. if water temp is low IHS temp is low and will handle temp spikes better. keep the IHS cool and the cpu stays cooler.
 
soulesschild said:
I think a number is what, 40C if you are using PETG tubing? Higher and it can deform. I know some vendors sell little plastic inserts to put at the ends of tubes to keep the rigidity if it does happen?
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If you really cannot avoid high water temps, you should look at acrylic or other material. But really (for me I should add), water temps of 45c defeats the point of watercooling. Why throw hundreds of dollars at this to only get a few degrees better than air cooling?
 
thesmokingman said:
If you really cannot avoid high water temps, you should look at acrylic or other material. But really (for me I should add), water temps of 45c defeats the point of watercooling. Why throw hundreds of dollars at this to only get a few degrees better than air cooling?
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or worse. to the component is like sitting in a 45c room.
 
pendragon1 said:
or worse. to the component is like sitting in a 45c room.
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Well, not quite. If you compare it to being attached to a traditional metal heatsink, we are comparing the water temp to the heatsink temp, not to the air temp.

Still, it does kind of defeat the purpose of water cooling.
 
During the day, my coolant temps sit around 30-31C when doing just simple things like web browsing, e-mails, videos, etc. Under extended gaming sessions (RDR2, for example), it will get up to around 36-37C. Doing CPU burner tests (Furmark CPU burner, for example), mine will peak around 40-41C, but stay closer to the 39-40C mark. On a cold night when nothing is going on, just idling, coolant temps may creep down to as low as 28C. To compare, my air cooled RTX 3090 FE sits around the 28-30C mark when idling and doing light load stuff and will drop down to as low as 24-25C on a cold night when everyone is asleep.

My setup for right now is just the CPU being water cooled. I have a Ryzen 9 3900XT with an all-core overclock (4.45GHz/4.45GHz/4.3GHz/4.25GHz at 1.256v) being cooled with an Optimus Foundation AMD waterblock, EKWB Quantum Kinetic TBE 200 D5 water pump, and a Corsair XR7 240mmx54mm radiator. CPU temps when gaming peak around 68-72C (again, RDR2 as an example, other games peak lower) but averages lower than that. Doing an extended CPU burn the temps peak in 75-78C range. My home thermostat is currently set to 22C during the day and 20C at night. Based on a Acurite temperature gauge sitting a little over a foot from the intakes of my computer case, the ambient temp going into my case right now is between 23.5-24.5C. At night expect the temps to be a few degrees lower. My guess for the higher room temp versus my thermostat setting is due to having my PC, two laptops, two air purifiers, and a couple of warm bodies occupying the space. My living room and bedroom are sitting closer to the 21C mark.

I originally was going to have two 240mm x 54m radiators in the case, but I miscalculated my measurements. When I first measured, it was based on waterblocks where the inlet and outlets were horizontal. The Optimus waterblock has the inlet and outlet set vertical on the waterblock, and I am a few mm shy of being able to fit a fan on the radiator. As such, I was stuck with using just one radiator for now. A 240mm x 30mm radiator will fit just fine as a second radiator in the loop, so I may add that at a later point (especially, if I consider tying my GPU into the loop or creating its own loop). But what I am asking myself now is, when that time comes, should I keep my existing 240mm x 54mm radiator or replace it with a 280mm x 30mm? When I was originally building it out, I didn't go with a 280mm radiator because I was going to be losing room for an intake fan in the front. But since then, I have managed to add two intake fans elsewhere. My current radiator gives me more volume, but the 280mm would give me more surface area. The thickness of my 240mm only allows me to do a push fan setup whereas with the thinner 280mm, I will have to double check my measurements, I *might* be able to squeeze in a push/pull fan setup. It would be real close of not fitting.
 
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Digital Viper-X- said:
I'm more worried about the pump dying to high temps :) (also noise) I already ordered a new case and 2 x 360 rads... this was a newish build, but I used my old Core P3 to build it in, which is limited to a single rad unless I use some 3d printed rad mounts. (at this point it looks a bit odd, and takes a way from the finish)
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To be honest you could probably do better with decent fans. you could try flipping them around as well for the time being, fans usually perform better in push and especially bad ones do. If you want those bling fans you're gonna need tons of rad space to make up for the lack of airflow.
 
D-EJ915 said:
To be honest you could probably do better with decent fans. you could try flipping them around as well for the time being, fans usually perform better in push and especially bad ones do. If you want those bling fans you're gonna need tons of rad space to make up for the lack of airflow.
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I was thinking about getting some vardar fans, or ML140s, the Static pressure on these is not THAT much lower on the MLs, but even at full tilt, they are pulling a decent amount of air out of the rad, and it's hot.
 
Digital Viper-X- said:
I was thinking about getting some vardar fans, or ML140s, the Static pressure on these is not THAT much lower on the MLs, but even at full tilt, they are pulling a decent amount of air out of the rad, and it's hot.
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What rad are you using? My EK CE rads don't cool quite as well as I'd wished.
 
D-EJ915 said:
What rad are you using? My EK CE rads don't cool quite as well as I'd wished.
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That's a drag. What fans are you running with them?

The reason i ask is Ive had really good luck with eks ce (and xe) rads. Its been 5 or 6 years (quite possibly longer) since i ran them but they were solid. I even paired them with some cheapie 140mm yate loon highs.
 
so I am also building a water cooled system, ordered a coolant temp sensor that my motherboard can see. I have fans that on low are around 800RPM, and would like the system to be quiet as possible for as long as possible (not ramp up and ramp down often). What coolant temp is good to start ramping the fans? I was thinking make a fan curve that starts at 35c coolant temp and is 100% fans by 40c. Ambient ranges from 20-30c depending on season, but would rather set it and forget it.
 
As said above, it depends on what temp you want your components to run at. The best way is to put your system under full load (CPU and GPU) and see how hot your components are at each coolant temp.
 
Tsumi said:
As said above, it depends on what temp you want your components to run at. The best way is to put your system under full load (CPU and GPU) and see how hot your components are at each coolant temp.
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I will give it a shot end of week when I hope I am finally up and running. It is a CPU only loop so I am hoping to see 70c peak... but I guess I don't have anything to base that on.
 
mnewxcv said:
so I am also building a water cooled system, ordered a coolant temp sensor that my motherboard can see. I have fans that on low are around 800RPM, and would like the system to be quiet as possible for as long as possible (not ramp up and ramp down often). What coolant temp is good to start ramping the fans? I was thinking make a fan curve that starts at 35c coolant temp and is 100% fans by 40c. Ambient ranges from 20-30c depending on season, but would rather set it and forget it.
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That's close to what I have it set at currently. Silent until 35 degrees (GPU load pops it over 35) then it will ramp up to full by 42 degrees, it never crosses 42 with this setup, which is nice, but I really don't want to hear the fans at full :) (They aren't that bad at full as they're 140mm and not the best fans, but still too loud for me)
 
mnewxcv said:
so I am also building a water cooled system, ordered a coolant temp sensor that my motherboard can see. I have fans that on low are around 800RPM, and would like the system to be quiet as possible for as long as possible (not ramp up and ramp down often). What coolant temp is good to start ramping the fans? I was thinking make a fan curve that starts at 35c coolant temp and is 100% fans by 40c. Ambient ranges from 20-30c depending on season, but would rather set it and forget it.
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That is similar to how I have my radiator fan profile setup, but my fans start out at a higher RPM (1300 RPMs) and ramp up from there. For me and my case setup, 1300 RPMs I can barely hear them and these fans top out at 2200 RPMs. At 35C, they start to slowly ramp up to 1500 RPMs. By 40C they are at 1800 RPMs. If it ever gets too hot, they will max out at 2200 RPMs by 45C. Thankfully, in day to day use, it stays below 40C and I only ever see around 40-41C if I am doing an extended CPU burn test. The fans I am using are BeQuiet! SilentWings 3 120mm High Speed PWM fans. Their static pressure rating and noise levels spec'd out pretty well.
 
VirtualMirage said:
That is similar to how I have my radiator fan profile setup, but my fans start out at a higher RPM (1300 RPMs) and ramp up from there. For me and my case setup, 1300 RPMs I can barely hear them and these fans top out at 2200 RPMs. At 35C, they start to slowly ramp up to 1500 RPMs. By 40C they are at 1800 RPMs. If it ever gets too hot, they will max out at 2200 RPMs by 45C. Thankfully, in day to day use, it stays below 40C and I only ever see around 40-41C if I am doing an extended CPU burn test. The fans I am using are BeQuiet! SilentWings 3 120mm High Speed PWM fans. Their static pressure rating and noise levels spec'd out pretty well.
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okay so maybe I will try 35-45c as the fan curve. Once the rads are installed I will adjust idle speed to the highest speed I can barely hear. Gentle Typhoon 1850rpm fans.
 
VirtualMirage said:
That is similar to how I have my radiator fan profile setup, but my fans start out at a higher RPM (1300 RPMs) and ramp up from there. For me and my case setup, 1300 RPMs I can barely hear them and these fans top out at 2200 RPMs. At 35C, they start to slowly ramp up to 1500 RPMs. By 40C they are at 1800 RPMs. If it ever gets too hot, they will max out at 2200 RPMs by 45C. Thankfully, in day to day use, it stays below 40C and I only ever see around 40-41C if I am doing an extended CPU burn test. The fans I am using are BeQuiet! SilentWings 3 120mm High Speed PWM fans. Their static pressure rating and noise levels spec'd out pretty well.
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You should be aiming for a delta of 10c over ambient.
 
thesmokingman said:
You should be aiming for a delta of 10c over ambient.
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I don't personally like targeting deltas over ambient.

There is an ideal temperature for the conpenents to work at regardless of room temperature, which means if you operate in a warmer environment you need a more serious loop than if you operate in a cooler environment.
 
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