Question regarding a CPU+GPU Loop

[empyr]

Hi,

I'm currently using a 280mm radiator to cool my CPU only. However, i may have to re-done some stuff soon which means that opens up the possibility for adding the GPU onto the loop too.

However, I am quite sure the 280mm on its own would most likely not work very well. Therefor, I am wondering if anybody has tried using a thick 140mm radiator (HWLabs Nemesis 140 GTX)?

 

I can't imagine it will make things a lot better but surely it would not hurt, (ps: limited space in mind, don't think i could fit a 240mm or 280mm extra) so i am wondering if it's a terrible idea and i should just keep the CPU loop by itself.

 

If anybody has any suggestions or ideas, I'd love to hear from you.

 

[For Science!]

2 minutes ago, empyr said:

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Welcome to the Forums!

 

Better to have the extra radiator than not. Depends on the CPU/GPU combo but I think 420mm radiator should be able to keep things in check reasonably well. For a reference, I did a 8700K + 1080Ti in a single 360 mm radiator loop and I would say it was "borderline" worth it.

[W-L]

1 minute ago, empyr said:

-SNIP-

Welcome to the Forums! 

 

You can cool it just with a single 280mm rad but you may need to run your fans faster to compensate, if you can fit an extra rad in place that would be ideal since as a general rule of thumb you would want approx 360mm of rad space. 

 

 

[billstelling]

I'm running a 360 and 120, both thins, for mine. A 240 thin and a 140 thick should do about as well I would imagine.

[empyr]

8 minutes ago, For Science! said:

Welcome to the Forums!

 

Better to have the extra radiator than not. Depends on the CPU/GPU combo but I think 420mm radiator should be able to keep things in check reasonably well. For a reference, I did a 8700K + 1080Ti in a single 360 mm radiator loop and I would say it was "borderline" worth it.

 

Thank you!

 

What kind of temps do you get on that loop with the single 360mm, if you don't mind me asking?

 

8 minutes ago, W-L said:

Welcome to the Forums! 

 

You can cool it just with a single 280mm rad but you may need to run your fans faster to compensate, if you can fit an extra rad in place that would be ideal since as a general rule of thumb you would want approx 360mm of rad space. 

 

 

 

Thank you!

 

I'm kind of worried in that regard, I'm using a Nemesis 280 GTS due to the limited space and it's handling the CPU on its own quite well currently.

I don't think it will be able to handle the 980 Ti ontop unless i turn the fan speeds way up (I'd really prefer not to do that for obvious reasons :P)

 

7 minutes ago, billstelling said:

I'm running a 360 and 120, both thins, for mine. A 240 thin and a 140 thick should do about as well I would imagine.

 

Oh i see, my setup would be a 280mm (thin) and the 140mm (thick), I assume as W-L suggested, turning up the fan speeds on the 280mm would help a bit too.

 

 

I'm actually just worried that my current temps on the CPU will take a big hit due to this, so im a little hesitant.

 

[Cyracus]

The general rule I've heard is a fan for every component +1 so for cpu and gpu 3 fans, regardless of whether 1 3 fan rad or 3 single fan rads. As others mentioned you can get away with less rad space, but have to run the fans faster.

[For Science!]

1 minute ago, empyr said:

 

Thank you!

 

What kind of temps do you get on that loop with the single 360mm, if you don't mind me asking?

 

It's in my Ncase M1 build log, but basically using Realbench as a stress test for GPU and CPU simultaneously, I got 75 degrees on the CPU and 54 degrees on the GPU. Both as "stock" (ASUS stock, so thats all auto-voltage with MCE enabled).

 

I also comment on it in the build log since I had the chance to compare air cooled GPU + 240 mm radiator AIO on the CPU. In this scenario the GPU is 12 degrees hotter, whereas the CPU is 15 degrees cooler (when compared to a custom loop). So the whole system is 3 degrees hotter by including the GPU in the loop and only adding a 120 mm radiator. This is likely because of the power delivery cooling for the GPU.

 

However not having a blower style GPU in the case made the system much more quiet, which is the principle gain of watercooling in my opinion.

 

 

[billstelling]

5 minutes ago, empyr said:

 

Thank you!

 

What kind of temps do you get on that loop with the single 360mm, if you don't mind me asking?

 

 

Thank you!

 

I'm kind of worried in that regard, I'm using a Nemesis 280 GTS due to the limited space and it's handling the CPU on its own quite well currently.

I don't think it will be able to handle the 980 Ti ontop unless i turn the fan speeds way up (I'd really prefer not to do that for obvious reasons :P)

 

 

Oh i see, my setup would be a 280mm (thin) and the 140mm (thick), I assume as W-L suggested, turning up the fan speeds on the 280mm would help a bit too.

 

 

I'm actually just worried that my current temps on the CPU will take a big hit due to this, so im a little hesitant.

 

33c at idle, 50ish under load.. I go from pump/res to the cpu, then to the 120 and from there to the gpu, up to the 360 and back to the pump.. I could more than likely get by with just the 360..

[empyr]

25 minutes ago, Cyracus said:

Quote here..

Interesting. Thanks for the tip

 

24 minutes ago, For Science! said:

Quote here..

That's pretty good man, looks good too I fully agree, it's one of the main reasons i want to get it under water. I hate the fucking fans when they ramp up :-P

Appreciate the advice.

 

20 minutes ago, billstelling said:

Quote here..

Very nice temps, I go from Res/Pump > 280 > CPU > Back currently, adding the GPU would be CPU > 140mm > GPU > Res/Pump.

 

[Cyracus]

19 minutes ago, empyr said:

CPU > 140mm > GPU > Res/Pump.

as an aside, rad placement doesn't matter, separating the cpu and gpu with one won't provide any real gains, but if it creates a look you like then that's cool. Sources: Jay, Linus, Kyle, and Paul

[Mick Naughty]

I run a 280 and 140 on my current rig. Cant really say its good or not as some base it on sound. I have an extra card and back plates adding heat to the loop but a single 280 would be great for a card and cpu. Adding another 140 would be worth it to me if you have the room and airflow.

[billstelling]

1 hour ago, empyr said:

Interesting. Thanks for the tip

 

That's pretty good man, looks good too I fully agree, it's one of the main reasons i want to get it under water. I hate the fucking fans when they ramp up :-P

Appreciate the advice.

 

Very nice temps, I go from Res/Pump > 280 > CPU > Back currently, adding the GPU would be CPU > 140mm > GPU > Res/Pump.

 

you want your pump after the rad.. They need to be kept as cool as possible. The pump for my xspc pump/res warns not to exceed 64c for example. It can effect the performance of the pump as well as it's life.

[W-L]

22 minutes ago, billstelling said:

you want your pump after the rad.. They need to be kept as cool as possible. The pump for my xspc pump/res warns not to exceed 64c for example. It can effect the performance of the pump as well as it's life.

The order of the loop makes no difference, the rate at which the fluid flow through the loop is so high once it reaches equilibrium it will balance out the rate of cooling to the rate at which it's taking heat away from the components. You still want to keep the pump below 60C however but in most loops you will never see past 50C for fluid temps.

[billstelling]

I agree for the most part, still it's a best practices thing.. I would not want two or three gpu's dumping into my pump before going though a rad so the fluid can be at it's lowest temp when encountering the pump.

As temp increases, the pump becomes less effective and as a whole this is not something that would noticeably effect the average system, it does however effect overall long duration performance when running under heavy load for extended times as well as how fast temps climb. While it can be negated by rad and res size, case size plays a role in just how much cooling you can put it a system and have it cool effectively under such loads.. By limiting the exposure to high temps at the pump, it allows it to run more efficiently for longer before heat has more of an effect on flow, which in turn effects the overall performance of the loop and it's maximum performance.

While you will eventually reach that equilibrium in temp either way, it will take a bit longer to get there..

 

[W-L]

1 hour ago, billstelling said:

-SNIP-

Yes and no, we're talking a marginal amount of a degree or two, it makes no difference once everything gets to equilibrium, when you take temps or any readings it should always be done at that point as that is when the system is perfectly balanced.