More Radiator(s)?

[Zammin]

Hi everyone!

 

I am currently running a custom loop in the popular Lian Li PC-O11 Dynamic case with two radiators. One is an EK XE360 in the top, the other is an XSPC EX360 mounted vertically in the second chamber. Both radiators are exhausting air out of the case, and air is brought into the case through the fully vented floor and rear of the case via negative pressure. This setup has been working well for my 8700k and 1080Ti. However I am upgrading to a 9900k and a 2080Ti very soon, both of which output more heat than my previous components. I'm also using a Maximus XI Formula that cools the VRMs with water, so that will be a little bit more heat in the loop as well. 

 

To help with the additional heat load, my plan was to add another radiator to the loop. The only free space left is the floor, so I bought a EK PE240 to mount to the floor with the fans pulling air through the radiator and into the case. Now the dilemma I am in right now is that someone told me I could be hurting my cooling performance instead of increasing it because the 240 radiator will heat the air going into the case, which means the other radiators will be fed with warmer air. I'm still not sure about this as I've always been led to believe that more radiator capacity/surface area is always better than less, even if the air is warmed up by one radiator before passing through the next. I see plenty of builds online running radiators in both intake and exhaust, including most PC-O11 dynamic builds with radiators on the floor.

 

I've been googling for a while now and I can't seem to find any definitive answers or articles on the matter. At this point since I'm unsure, I do plan to test both scenarios with some soft tubing first to find out which is best before finalising the build with hard tubing. However I still wanted to hear what some of you experienced watercooling enthusiasts had to say on the matter. Here is a rough draft of how I plan to setup my loop. Do you think adding the third 240 radiator in the floor will still gain me better cooling performance? Or do you think it will hurt performance instead?

 

EDIT: The picture is a little misleading in that it makes it look like I'm exhausting air forward out the front of the case, but the radiator and fans are actually mounted to the side blowing air out the side of the case (the radiator is in the second chamber with the PSU etc). Apologies for the confusion, it was hard to represent it that way from a side perspective.

 

[narrdarr]

your not going to hurt the temps as everything will stabilize at 1 temp.

but your going to want positive pressure. bottom and side rads should be intakes make top rad exhaust and rear fan exhaust 

[Spotty]

You won't be adding any extra heat in to the loop by having another radiator on the intake. The hot air in the case is a result of that heat already being removed from the loop on the 240mm bottom rad. So the energy in that warm air is energy that has already been removed from the loop (cooling the loop). So no, it won't make the cooling worse.

You'll be adding more mass (water) to be heated, and your surface area to cool it with will also increase with the extra radiator, so in theory you should see improvement to temperatures.

It might have been a different situation if you had an air cooler on the GPU, which would then run hotter because it would have warmer case air to try and cool itself with, but since everything is water cooled through the loop it's fine.

 

Personally I would swap the front rad around so it's an intake and have the top as the only exhaust, but if you like negative pressure then that's up to you.

 

22 minutes ago, Zammin said:

This setup has been working well for my 8700k and 1080Ti. However I am upgrading to a 9900k and a 2080Ti very soon, both of which output more heat than my previous components.

I would say that the RTX2080Ti probably doesn't generate much more heat than the 1080Ti. They're both 250W-ish TDP cards. 9900k would probably be a bit hotter though.

[corrado33]

You might want to make sure your pump can handle 2 360mm rads plus an additional 240mm rad. That's.... a lot of pressure. 

[Zammin]

56 minutes ago, narrdarr said:

your not going to hurt the temps as everything will stabilize at 1 temp.

but your going to want positive pressure. bottom and side rads should be intakes make top rad exhaust and rear fan exhaust 

Thanks a lot for your input! Sadly the case does not have an option for a rear fan, I really wish it did! They put space for one of the O11-Air butnot for the O11-Dynamic

 

I'm not too worried about pressure balance if it's for for dust control, even with entirely negative pressure I don't get much dust in the case at all, and that's with no filters haha. It sits on mys desk so that may have something to do with it. Having negative pressure seems to allow for cool air to be pulled through the vented spaces of the floor and rear of the case so that may help I think.

 

49 minutes ago, Spotty said:

You won't be adding any extra heat in to the loop by having another radiator on the intake. The hot air in the case is a result of that heat already being removed from the loop on the 240mm bottom rad. So the energy in that warm air is energy that has already been removed from the loop (cooling the loop). So no, it won't make the cooling worse.

You'll be adding more mass (water) to be heated, and your surface area to cool it with will also increase with the extra radiator, so in theory you should see improvement to temperatures.

It might have been a different situation if you had an air cooler on the GPU, which would then run hotter because it would have warmer case air to try and cool itself with, but since everything is water cooled through the loop it's fine.

 

Personally I would swap the front rad around so it's an intake and have the top as the only exhaust, but if you like negative pressure then that's up to you.

 

I would say that the RTX2080Ti probably doesn't generate much more heat than the 1080Ti. They're both 250W-ish TDP cards. 9900k would probably be a bit hotter though.

Thank you!

 

Yeah that is what I originally expected, I didn't think the warm air from the 240 would be enough to really hurt performance. I understand that in the absolute ideal scenario, one would want to have fresh air moving through all the radiators but in a small case like this it's not really possible or practical.

 

Yeah it's the 9900k that I'm most concerned about haha. The 2080Ti only runs a few degrees hotter than the 1080Ti under water from what i have read.

[narrdarr]

2 minutes ago, Zammin said:

Thanks a lot for your input! Sadly the case does not have an option for a rear fan, I really wish it did! They put space for one of the O11-Air butnot for the O11-Dynamic

 

I'm not too worried about pressure balance if it's for for dust control, even with entirely negative pressure I don't get much dust in the case at all, and that's with no filters haha. It sits on mys desk so that may have something to do with it. Having negative pressure seems to allow for cool air to be pulled through the vented spaces of the floor and rear of the case so that may help I think.

i still think neg pressure in this setup might be a bit extreme and may result in a less preforming loop

[Zammin]

46 minutes ago, corrado33 said:

You might want to make sure your pump can handle 2 360mm rads plus an additional 240mm rad. That's.... a lot of pressure. 

Yeah I have considered this, but it should be fine I think. It's an EK D5 pump in a Heatkiller Tube 200, and the EK rads are not very restrictive, same for the EK velocity CPU block, it's very low restriction. What I will do though is when I run my initial testing with the soft tubing, I will put my barrow flow meter on the inlet to the pump to measure flow rate and see how it handles.

 

39 minutes ago, narrdarr said:

i still think neg pressure in this setup might be a bit extreme and may result in a less preforming loop

Interesting, I thought negative pressure was only an issue for dust control but I could be wrong. It does allow for fresh air to be pulled into the case from the ventilated areas that don't have fan mounts though.

 

Previously when I first setup my system I had the side rad as intake and the top as exhaust, but I got slightly better cooling performance when I changed them both to exhaust for full negative pressure.

 

I do appreciate your thoughts though, I will have to do a bit more reading on the effects of positive and negative pressure.

[corrado33]

2 minutes ago, Zammin said:

Yeah I have considered this, but it should be fine I think. It's an EK D5 pump in a Heatkiller Tube 200, and the EK rads are not very restrictive, same for the EK velocity CPU block, it's very low restriction. What I will do though is when I run my initial testing with the soft tubing, I will put my barrow flow meter on the inlet to the pump to measure flow rate and see how it handles.

As for negative or positive pressure, there are components on the mobo that are still air cooled (VRMs, etc). Theoretically the temp of those would increase with hotter air inside the case, practically it probably won't make a difference. Just monitor them once you do this that's all.

[Zammin]

34 minutes ago, corrado33 said:

As for negative or positive pressure, there are components on the mobo that are still air cooled (VRMs, etc). Theoretically the temp of those would increase with hotter air inside the case, practically it probably won't make a difference. Just monitor them once you do this that's all.

Cheers! I'm running a Maximus XI Formula though so the VRMs are water cooled

 

Also for some reason the title of my thread has been changed haha, maybe someone thought the original title was too long.

[corrado33]

15 minutes ago, Zammin said:

Cheers! I'm running a Maximus XI Formula though so the VRMs are water cooled

Oh nice! In that case I'd run positive pressure (front fans in instead of out) since seemingly nothing in your case is air cooled. At least nothing important. 

 

Honestly, just try both and see which gives you better results. 

[Zammin]

7 minutes ago, corrado33 said:

Oh nice! In that case I'd run positive pressure (front fans in instead of out) since seemingly nothing in your case is air cooled. At least nothing important. 

 

Honestly, just try both and see which gives you better results. 

The image makes it look like the fans and radiator are on the front of the case, but they are actually on the side facing outward (the radiator is in the second chamber with the PSU etc) but yeah I get what you're saying, it's still technically at the front of the case. I'm hoping by using soft tubing initially for testing I can test various scenarios to see which works the best before finalising everything with hard tubing. It's still very helpful to get opinions from you guys beforehand so I know what things I need to take into consideration and what I might expect to achieve.