Water cooling loop optimization

[southpark11235]

I build a custom water loop to cool my i7-7700k and 1080 ti. Right now it is doing a good job cooling the GPU, but the CPU is getting warmer than I would like, for how big the radiator and pump are. Under a stress test the GPU will quickly get up to 38C and stay there fairly steady. Even after 30 minutes the GPU will still be at 38C and the coolant coming out of the pump is at room temp. I am happy with these temps and that is what I expect with how overkill everything is. The CPU on the other hand under a stress test will shoot up to 60C and bounce between 50C and 60C every few seconds. This is with no overclocking. It gets even hotter when I overclock it. If I remember correctly it was peaking near 80c with the same 10c bounce with the hottest OC I tried. I currently have the CPU stock clocked has I want to get the temps under control before I spend the time dialing the prefect OC. The water coming out of the pump is always at room temp and turning the pump up does not seem to help. Currently I have the water flowing from the radiator to the pump then a Y splitter into the GPU and CPU blocks separately then into a Y merge then the reservoir. I think maybe the GPU is less restrictive and is taking most of the water flow from the CPU and that is what is casing my issue. That or there is something else I am missing and hopefully someone here would know what that is. Currently I have two ideas on how to fix the issue. One, I could ditch the Ys and run from the pump to the CPU to the GPU directly. Two, I could get a second pump and split before them so the CPU and GPU would each have there own pump. I drew some simple pictures of the loop to make it clear what it is now and what I am proposing. 

[Enderman]

You should not be putting a CPU and GPU block in parallel........................................

You can only do that for GPUs because all the waterblocks are identical.

[LIGISTX]

Would really help to know what hardware we are dealing with here... I run a 8700k @ 5 GHz, and lots of rad space. 5 140mm fans worth in total, and 280 worth of them are 60mm thick rads and the other 3 are 45 thick. So I have "a lot" of radiator with the intent of it being dead silent... which was successful.

 

So, knowing what pump and rads you have would help a lot here. That said, there is no way your 1080ti is at 38c... Right now I am at idle and my 2080 is at 29, and my ambient room temp is about 75f. Under game load, it gets upt to about 49. 38..... can't be right, unless your ambient temps are "cold".

 

Also, look order really doesn't matter. All of the water in the loop is about the same temp, the water is moving so fast compared to the heat output and dissipation of the system, the water before your CPU and after will be almost the same temp... thus loop order is negligible. That said, as stated above, don't put them in parallel. Because of the reason I just described, its pretty pointless and likely will only make things worse.

 

Also, just because you have a great cooling solution doesn't solve the issues of crap Intel TIM being used under the IHS, its possible yours is just extra bad... When I delid my 4770k I dropped a full 20c, with less fan RPM which makes that not even a fair apples to apples. Likely dropped ~22-23c in reality. Thankfully my 8700k isn't to bad, I got a pretty decent chip.

[southpark11235]

Thanks, I though it was something I screwed up with the loop routing. I will try getting rid of the Ys and see if that does not fix it. If not I will try delidding. After all the time and effort I spent building everything it sucked to not get the temps I was hoping for. 

 

The radiator is about 31x18x2 inches counting the end tanks and the pump is a secondary coolant pump for a bunch of cars. https://www.amazon.com/gp/product/B00BHKX9PA/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

[Mick Naughty]

May be stuff in the cpu block, clogging it. Or poor contact or Tim application. 

 

In do series on most of mine unless I prefer the looks of parallel. I don’t do Y setups though. 

[For Science!]

13 hours ago, southpark11235 said:

 

I assume the 7700K is not delidded? then its probably about expected performance.

[Blai5e]

@southpark11235 - If you do parallel, you would simply loop off the GPU to the CPU and return back to the GPU discarding the Y connectors.

 

 

I have my rig plumbed in parallel (CPU & 2 x GPU) with the split being performed via a distribution plate and have only notice a 1~2°C temperature difference under load (albeit, I did add 10% to the PWM duty cycle for the pump).

[BigBlackRat]

fixed

 

 

[southpark11235]

Well, I redid the loop to as show on picture two and I think I just fried my 1080 ti like an idiot. A quick test shows slightly more stable temps but not much better. I think I am done for a while and I am going to forget about my PC for now. 

[thrasher_565]

i don't get all the y's in there. you should have the res feed in to the pump and the res higher then the pump. option 2 is what i would start out with later on you can play around.