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Loop order shouldn't matter unless you have serious flow issues. Temp difference shouldn't more then a few degrees if that at any point in the loop. Run your loop whatever way works best as long as the pump doesn't run dry it shouldn't matter what order it's in
No exactly. When Martin tested sandwiched radiator performance (effectively what this setup will be) he showed a measurable performance difference running the heat load to the rear radiator first, followed by the front radiator.

Its up to OP how he wants it done, but for efficiency sake, this is the best way (especially considering, if you really think about it, you lot changing the loop complexity much at all either way). But to your point, yes, generally a shorter loop is desired to maximize flow rates.
 

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If you want good temps and low noise you are going to have to really look at your air flow. and if your putting heat from one rad into the other rad you might as well only use one rad with double the fans for max flow. one 360 should do 600w decently with good airflow. everyone thinks you need more rad simply not the case. i use a 140mm for a 300+w gpu and i never see temps above 30c on the liquid even with the push pull fans at sub 800rpm (silent)

in other words get the air flow before you add more rad. You could be better off doing a single 140mm for rear exhaust and then 280mm or 360mm on top exhaust. this not only helps air flow through the case it also keeps the air inside the case cooler meaning the rest of your system will run cooler too.
 

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Might be worth doing a extra tall case so you can mount a 360mm under the psu and use the second 360mm on top. that way both are getting fresh air.

if getting a new case is what you want to do.
 

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Loop order shouldn't matter unless you have serious flow issues. Temp difference shouldn't more then a few degrees if that at any point in the loop. Run your loop whatever way works best as long as the pump doesn't run dry it shouldn't matter what order it's in
yep res then pump rest dont really matter to much long term loop temps will be 1-2c from point a to point z unless you have some very bad flow and then you already have bigger problems. Case wise i love my core x71 owned it about 5 years tons of options for rads i run a 420 in front and a 360 in bottom right now and use top to exhaust out hot air.

 

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Loop order shouldn't matter unless you have serious flow issues. Temp difference shouldn't more then a few degrees if that at any point in the loop. Run your loop whatever way works best as long as the pump doesn't run dry it shouldn't matter what order it's in
Shawn is correct. Loop order doesnt matter except the reservoir feeds the pump and it has to be higher than the pump to prevent it from running dry. I have two temp sensors in my loop. One where its leaving the pumps and one when its leaving the GPUs (last components. Once the loop is soaked they are never more than 1C different (usually less)
I still think your issue resides in the inability to pull the heat out of the loop be it the rad space or airflow. I dont recall seeing anything about fan flow direction....If you are pulling the heat into the case through one and out through the other its definitely going to result in higher temps. Dumping air cooled GPUs into the case then pulling that hot air through the rad will also increase loop temps. Only thing I can say is if I saw 40C Id be sh!tting bricks......big ones. 50C forget it. I keep mine in the 30C range under heavy load with some serious loads on it.
 

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You know... if you really want the lowest possible water temps (with standard water cooling, i.e. non-chiller), external radiator(s) is the way.
 

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Something no one ever mentions when building watercooling loops, but this showed me that doing the build in summer is actually a good thing. Then you know it will be better when weather will be cooler. Leading me to a question I had not anticipated: what do you guys do when it's 40°C ambiant temperature? It usually happens here in France at some point during summer.
I live in a third floor apartment directly under the roof and it often gets uncomfortable in the summer here in southern Germany, too. I don't think we've ever actually hit 40 in here but it often gets well into the 30's. When that happens I'm in no mood to sit and game and have my PC dump even more heat into the room. I turn it off and go sit in the Biergarten 😅
 

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When ambients are high the liquid will certainly follow. Even then that’s a high temperature. I run central AC and ambient never goes above 24C. My max loop temp is 6C above that with a heavy load on a 10980XE and a pair of 2080Tis. 40C I’d still not expect more than 46C loop temp, not that it will ever happen even during a utility interruption. I have a dual conversion UPS on my rig and 30 seconds after the utility power goes my 20kW generator starts and has an automatic transfer switch. Enough power to run the entire house and then some so long as the natural gas supply isn’t cut off which has never happened. Longest run on Generator was 19 hours during hurricane Sandy. I was the only one in the neighborhood with a whole house generator. Had extension cords running to some of my neighbors so they could run their refrigerators. One got greedy and had to cut him off. Breaker tripped, he comes knocking on the door. He is the only one on that 20A breaker. No way a refrigerator and even adding a window AC would trip it. Come to find out he was trying to run his entire house off of a 20A circuit and 200 ft of 14 gauge extension cord. I went over and he had it tied into his main breaker panel. I’m like you can’t do that. Run just your refrigerator and your choice of an AC or maybe microwave or more importantly you better watch your sump pump so the basement doesn’t flood out. In that case unplug the refrigerator and plug in the pump so it can pump down. So reset breaker and 30 mins later he’s at the door again. I unplugged the cord and told him sorry, you are on your own. Everyone else plugged in isn’t having problems so you obviously aren’t listening. You want whole house coverage, go buy a whole house generator.

Generator had been installed for several years then after the incident he had the balls to start calling the PoPo filing a noise complaint when my generator did it’s self test every 2 weeks on Wednesday at noon. After the second trip out the quit coming.
 

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You know... if you really want the lowest possible water temps (with standard water cooling, i.e. non-chiller), external radiator(s) is the way.
Valid point. I’m about to strip half the rads out of my case and put this monster in the loop. Just a lot to do and no time to do it in. All assembled, tubing cut with quick connects. Have to turn GPUs back horizontal. The vertical mount looks awesome but blocks ALL the PCIE slots and the Start, retry, safe start, safe mem and bios select switch on the bottom left corner not to mention being able to access any of the bottom MOBO connectors. That and it will open up a slot for a PCIE IN/OUT header threaded G1/4 both sides. Then I’ll have to rework some internal hard tubing and go back to Mayhems pastel red, have plenty but just running DW with antimicrobial ATM following my annual flush and changing flow meter to aqauacomputer Next Flowmeter. Before I go there I also wanna make a final decision on what block is going to live in it. An Optimus foundation is in there now (mostly to prove/disprove another members claim it outperforms a Sig V2 and PPCs had them and I had a butt load of points and 15% off sale going on so it cost me like $60). Well it’s not the better of the two. The Sig V2 with internal Oring pulled is better and the EK magnitude with the flat cold plate that isn’t completely flat better yet. I ordered a blemish flat Sig V2 that’s not all that blemished. Figured I’d give that a go and if it doesn’t cut it the EK magnitude will go back in. Honestly I get better temps with a Heat Killer IV Pro than with the foundation. Thing is they didn’t account for IHS bow on HEDT and no way to adjust it. Seems like no two are exactly the same and I’m not going to lap away my warranty just yet.


2514065
 

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Shawn is correct. Loop order doesnt matter except the reservoir feeds the pump and it has to be higher than the pump to prevent it from running dry. I have two temp sensors in my loop. One where its leaving the pumps and one when its leaving the GPUs (last components. Once the loop is soaked they are never more than 1C different (usually less)
I still think your issue resides in the inability to pull the heat out of the loop be it the rad space or airflow. I dont recall seeing anything about fan flow direction....If you are pulling the heat into the case through one and out through the other its definitely going to result in higher temps. Dumping air cooled GPUs into the case then pulling that hot air through the rad will also increase loop temps. Only thing I can say is if I saw 40C Id be sh!tting bricks......big ones. 50C forget it. I keep mine in the 30C range under heavy load with some serious loads on it.
Not be beat the dead horse but I'll repeat. According to Martin's testing, loop order does matter if you have two radiators running in air flow series (less of a difference if you can introduce a secondary source of air intake to lower case ambient temps). Directing the heat load to the exhaust radiator before the intake radiator will net about 1-2*C better temps than running the heat load to your intake radiator and then the exhaust radiator. You can run your pump/res in any part of the loop you want but if you want max efficiency always ensure the heat load goes to the exhaust radiator before the intake radiator when you have multiple radiators in series (air flow).

Why is this? While you are correct, the deltT of any two parts of a loop generally won't exceed 1-2*C, remember water has a tremendous specific heat value and the amount of joules it takes to raise the temperature by 1*C is a lot more than you think.

Now I know some people will say "why put so much effort for only 1-2*C performance gain?" but if you really look at it, its almost no effort at all to choose one loop order over the other. Little effort for little gain is a no brainer for me (y)

Lastly, to a point I made earlier, when running a intake and exhaust radiator; (first off, its not recommended), running your rear exhaust fan (and any other fan you have in your case) as an intake fan will help increase efficiency of your exhaust radiator by keeping case ambient temps lower.

However, I still recommend both radiator run as intake (then loop order won't matter as long as its kept as short and simple as possible).
 

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Not be beat the dead horse but I'll repeat. According to Martin's testing, loop order does matter if you have two radiators running in air flow series (less of a difference if you can introduce a secondary source of air intake to lower case ambient temps). Directing the heat load to the exhaust radiator before the intake radiator will net about 1-2*C better temps than running the heat load to your intake radiator and then the exhaust radiator. You can run your pump/res in any part of the loop you want but if you want max efficiency always ensure the heat load goes to the exhaust radiator before the intake radiator when you have multiple radiators in series (air flow).

Why is this? While you are correct, the deltT of any two parts of a loop generally won't exceed 1-2*C, remember water has a tremendous specific heat value and the amount of joules it takes to raise the temperature by 1*C is a lot more than you think.

Now I know some people will say "why put so much effort for only 1-2*C performance gain?" but if you really look at it, its almost no effort at all to choose one loop order over the other. Little effort for little gain is a no brainer for me (y)

Lastly, to a point I made earlier, when running a intake and exhaust radiator; (first off, its not recommended), running your rear exhaust fan (and any other fan you have in your case) as an intake fan will help increase efficiency of your exhaust radiator by keeping case ambient temps lower.

However, I still recommend both radiator run as intake (then loop order won't matter as long as its kept as short and simple as possible).
Yeah Martin is an Idiot which is why his productions ceased like 20 years ago. This myth has been proven to be incorrect time and again. Once the loop is soaked the temp will be the same throughout give it take 1C. I’ve done it a million different ways from Sunday over the last 30 years and found it doesn’t make a difference in the end. Even IF it dropped temps by 1-2C the result on your components would be virtually nil.
What his point was is more about air flow and not about loop order. I hear people crying about positive pressure that I’ve learned is a crock of BS. Yeah is will keep more of the dust at bay but rads should all be exhaust and additional “fans only” for fresh air make up. No matter how you run the loop if you have one rad exhausting and another as intake the exhaust is going to be pulling hot air from the intake through it or worse yet air cooled GPUs and pulling that heat through a rad.
Best option remains…..External rads or a chiller that maintains loop at ambient unless you want to fight condensation.

If everything is kept internal shorter simplistic routing is the best recipe for fluid dynamics.

If you are trying to do a decent performing liquid cooled build in a tiny a$$ case you are setting yourself up for failure from the beginning.
 

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Yeah Martin is an Idiot which is why his productions ceased like 20 years ago. This myth has been proven to be incorrect time and again.
No he isn't and no it hasn't.
 

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Please show me a loop where any component be it the CPU or GPU heat up the water by 2 degrees in one section only and cools down in another section that is running 1GPM.

Two radiators or not I’d love to see this setup with such differences in temp.
I just know my my experience with temp sensors on every inlet/outlet that this is wrong but please prove me wrong. And not using benchmarks from 20 years ago
 
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No he isn't and no it hasn't.
Yes he is and yes it has.
Even Jay No sense knows better. The only point you will measure any temperature change is going into and coming out of a radiator as rad surface area and fans dictate the loop temp. The order DOESN'T matter. Depending on the rad you may see a 2C DROP from inlet to outlet but back home in the res and the rest of the loop its within 1C or less. If you are getting different then you have a pi$$ poor loop with screwed up airflow and a weak a$$ pump.

Now if you are a nimrod and pull hot air from air cooled GPUs through a rad running exhaust then is will heat up your loop BUT it doesn't matter what order the loop is in. Clean shorter runs are more practical. The only dynamic that will change in any loop REGARDLESS of the order of the fluid flow is the case and how fans are set up. If you pull hot air into a case though a rad then exhaust that hot air though another rad it will not perform as well but guess what.....THE LOOP ORDER DOESNT MATTER!! What does matter is airflow though the rads and that the intake to the rads are fresh ambient air or recycled hot air from an air cooled GPU or another rad. This is what kicks most peoples butts, airflow. I even noted it when I built my current rig and had to run two GPUs on air as no blocks existed at the time of release. My loop temp was actually hotter than with the GPUs with blocks on them and in the same loop. Pull the door so that hot air isn't getting pulled out though a rad and problem solved until I got my water blocks. I've redone the loop I have several times over, just messing with different runs, putting in a Distro the I subsequently pulled because it ran the CPU and GPUs in parallel Starving the GPUs because liquid takes the path of least resistance and caused my GPU to run warmer. That wasn't about loop order, it was about a crappy component. In the end what went to what first DIDNT MATTER!

Jay no sense take on it.

Martins flow rate estimator most recent version from the stone age with Dtek blocks, swiftech blocks and Danger Den that has been out of business so long its past a distant memory. I used a few of their blocks last millennia with the prongs sticking up out of the cold plate and just in and out. Pretty sure I still have a couple laying around that I replaced with Dtek Fusion on an Athlon FX build older than my adult children. Back then.......LOOP ORDER DIDNT MATTER. Way back then there were no serial pump tops. D5 Pumps were all Laing or swiftech.

In the end its about correct air flow, having enough rad surface area to dissipate the heat of your components and enough pump/s with enough a$$ to keep a decent flow rate. Oh yeah that old BS about 120 per component also went out the window long ago. That would put me in the same boat as the OP with a high liquid temp as no 360 on the planet is going to cool an overclocked 10980XE and a pair of overclocked 1080Tis. A 480XE, GTR420, GTS360 and 360SE is capable which is nearly 4 times as much as the 120 per component rule that also went out the window 20 years ago. Along with Martins liquid flow calculator........
 

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Please show me a loop where any component be it the CPU or GPU heat up the water by 2 degrees in one section only and cools down in another section that is running 1GPM.

Two radiators or not I’d love to see this setup with such differences in temp.
I just know my my experience with temp sensors on every inlet/outlet that this is wrong but please prove me wrong. And not using benchmarks from 20 years ago
Well gonna have to give some wiggle room on that flow rate to 1G/day.
 

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You do realize Martin and Skinee's most notable discovery during the early days of watercooling was that the loop temperature remained relativy constant... You're arguing against Martin using a point he and Skinee discovered in their testing. Their work was what convinced the watercooling community to ignore loop order and maximize flow rate. Look down. Your standing on the shoulders of giants.

But to get back to my point, I'm not talking about loop temps, I'm talking about radiator efficiency.

OP, it's not a big deal but if you want to maximize efficiency, if you are running intake and exhaust radiators, it's not too difficult to rout your loop to run your heat load to to exhaust radiator first while maintaining the shortest loop order for maximum flow rate. As Justin oddly gets right in his rant, it's about heat dispensation and this will maximize heat dissipated .
 

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You do realize Martin and Skinee's most notable discovery during the early days of watercooling was that the loop temperature remained relativy constant... You're arguing against Martin using a point he and Skinee discovered in their testing. Their work was what convinced the watercooling community to ignore loop order and maximize flow rate. Look down. Your standing on the shoulders of giants.

But to get back to my point, I'm not talking about loop temps, I'm talking about radiator efficiency.

OP, it's not a big deal but if you want to maximize efficiency, if you are running intake and exhaust radiators, it's not too difficult to rout your loop to run your heat load to to exhaust radiator first while maintaining the shortest loop order for maximum flow rate. As Justin oddly gets right in his rant, it's about heat dispensation and this will maximize heat dissipated .
Not what you said in your "Dead horse post". You said 'Loop order does matter which is why a few of the more seasoned people, me included, gave you flack about. There is no argument to be had on how you set up air flow, I think we are in the same book but possibly different pages there. Rad surface area and air flow as well as direction of flow has everything to do with loop temps. Best thing hands down is external rad with a few fans in your case for ventilation. That way you are always pulling/pushing (or both) fresh air though the rad. Better yet if you have a window near by you can put an external rad pulling in during the winter to get some crazy low loop temps and during the summer if you have conditioned space in the window blowing out so the heat is going out the window instead of dumping in the room.
 

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I've always maintained that rads work best pulling cool air in. However unless you have a case capable of then exhausting the hot air from the rads, you'll never achieve good results. Unfortunately case designs are pretty ****e when it comes to water cooling. I consider myself lucky to have a Corsair 900D but even that isn't perfect. Such a shame that Caselabs went under!
 
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Not what you said in your "Dead horse post". You said 'Loop order does matter which is why a few of the more seasoned people, me included, gave you flack about. There is no argument to be had on how you set up air flow, I think we are in the same book but possibly different pages there. Rad surface area and air flow as well as direction of flow has everything to do with loop temps. Best thing hands down is external rad with a few fans in your case for ventilation. That way you are always pulling/pushing (or both) fresh air though the rad. Better yet if you have a window near by you can put an external rad pulling in during the winter to get some crazy low loop temps and during the summer if you have conditioned space in the window blowing out so the heat is going out the window instead of dumping in the room.
Yes, it does.

I'm not sure where I'm loosing you but I'll try explain, however when you said Martin was an idiot and tried to prove him wrong referencing Jays2cents recreation of a test that was arguably the most significant discovery from Martin's and Skinnee's work, I don't think I'm talking to someone who wants to learn more than wants to just be right.

Some background on your idea that "loop order doesn't matter":
Right off the cuff, to say "loop order doesn't matter" is, at face value, completely wrong. While I understand what you are TRYING to say, LOOP ORDER MATTERS A LOT in that (thanks to Martin's and Skinee's work) we know loops should be ORDERED as simple as possible. Below is some reading if you want, of my recollection of Martin's and Skinee's work. I'm remembering this from over a decade ago so I could be wrong on some details but overall I think it captures the premise of what I'm trying to say:

First point
Martin and Skinee proposed over a decade ago that flow rate was the most important part of a loop design. There was a theory before this that loops HAD to have a radiator between each heat load (CPU => Rad => GPU) which DID help temps but what Martin showed was that A: the temp benefits were not significant and at times not measurable (<1*C) and B: the resulting loop tended to be more complex than it had to be which adversely affected flow rate. He also showed that as flow rate increased, the DeltaT between any point of a loop diminished (as Jays2cents shows in his testing). His resulting assumption was that, when a loop reaches a particular flow rate (I believe it was 1gal/min) the temperature across the entire loop normalizes within 1*C. This invalidated the theory that CPU's and GPU's heated the water to a significant temperature requiring radiators to be strewn throughout a loop. HOWEVER, he did admit (IIRC) there was SOME benefit to doing this, as long as loop complexity was kept at a minimum.

Second Point
His testing also showed that 1gal/min was the minimum recommended flow rate for a loop with diminishing returns as flow rate increased over 1.5 gal/min (IIRC) and showed that proper flow rate had a much bigger affect on temps than having complex tubing/radiator labyrinths. His conclusion was it was more important to make a simple loop with a maximum flow rate than to put a radiator in between every heat load in your loop. And remember, a decade ago, people were watercooling (in addition to 1-2 CPU's and up to 3-4 GPU's) VRM's, chipsets, memory, HDD's, etc... so loops got complex fast.

To summarize, having a short and simple loop that maximized flow rate was the most important part of a loop design.

Third Point:

Martin demonstrated in his "sandwich" radiator testing that running the heat load to the exhaust radiator prior to the intake radiator netted about a 1*C benefit vs the opposite.

In conclusion
When running an intake and exhaust radiator, LOOP FLOW can help radiator efficiency by exhausting a majority of the heat straight out of the case rather than straight into the case to then be recirculated through another radiator. While the joules of heat dissipated won't make a readily measurable effect on the water temperature (due to the high specific heat of water), it still results in BETTER RADIATOR EFFICIENCY when the loop is ORDERED CORRECTLY.

Now the question is, can you maximize radiator efficiency without over complicating a loop? I'm pretty sure the answer is YES. So as I said, its a small gain in efficiency but its also a small investment in effort which is a no brainer for me. LOOP ORDER MATTERS. Even if its just a small gain.
 
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