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Water cooling multiple CPU's (4)

4.7K views 16 replies 10 participants last post by  tsm106  
#1 ·
Hey everyone,

I've water cooled quite a few systems, I just have a quick question regarding something entirely new to me...

I'm designing a liquid cooling system for a Quad CPU system, and I wanted to know if I should designate a loop for each CPU, or run each one consecutively in the same loop? Run through two CPU's, back to a rad, then to the other two? How should I go about setting this up?
 
#2 ·
I've seen people with a continues loop between two cpu ie sr-2 build
and as far as I can remember B Neg who has sr-2 build has minimum temp difference between the cpu running it that way

Are you planning dual loop?
I would personally make a dual loop and run two cpu in one loop to be honest
that way you can maybe OC the cpu better and have lower temp
post us how it goes, thats an interesting idea
smile.gif
 
#3 ·
I run my 2 chips in series with heavy oc's,the temps are pretty even between the 2.
I don't think there is a quad socket made that overclocks so you could do a 4 CPU loop,I have 3 670s in the same loop,another 2 CPUs instead shouldn't make much difference.
 
#4 ·
I am not aware of any systems running quad CPUs.
Would they share the load at a times or would some of them get loaded while others are more or less idling? This would be an important factor in answeing your question properly.

Cheers
cheers.gif
 
#5 ·
Quote:
Originally Posted by PepeLapiu View Post

I am not aware of any systems running quad CPUs.
Would they share the load at a times or would some of them get loaded while others are more or less idling? This would be an important factor in answeing your question properly.

Cheers
cheers.gif
Server motherboard?
 
#6 ·
Quote:
Originally Posted by xNovax View Post

Server motherboard?
Yeah okay maybe.
I never played around with servers here. Would the board load all CPU's equally like an SLI GPU's type of thing? Or would the CPU's have different loads and heat outputs at different times?
 
#8 ·
Quote:
Originally Posted by PepeLapiu View Post

Quote:
Originally Posted by xNovax View Post

Server motherboard?
Yeah okay maybe.
I never played around with servers here. Would the board load all CPU's equally like an SLI GPU's type of thing? Or would the CPU's have different loads and heat outputs at different times?
It could be both depending on the scheduler. It's no different than multi-core cpus, just on a larger scale.
 
#10 ·
Reasons for a single loop

1) Cost
With a single loop, there is only one pump to buy, maybe two for power/redundancy. With multiple loops, you will need multiple pumps no matter what. More fittings to buy, multiple reservoirs.

2) Maintenance
Only one loop to build/bleed/drain/clean/monitor.

3) Noise
Less noise from a single (or dual) pump over 4 separate pumps.

4) Heat
Pumps do inject heat into your loop, a single pump won't heat up your loop as much as 4 would heat up their individual loops.

5) Safety
With multiple loops, you multiply the chances of pump failure and leaks by the amount of loops. Should one of the loops fail, it's CPU will heat up and the rig needs to be stopped. With a single loop, there are fewer chances of loop failure. And you can always add a second pump for more power and more redundancy. A pump fails and the other one keeps the show on the road.

6) Performance
Most importantly, you will get much better performance out of a single loop, especially if the CPU are unevenly loaded.. Imagine if you will 4 loops, one loop for each CPU and a 240 rad in each loop. So CPU-1 gets loaded and gets hotter while the other 3 are idling. That CPU-1 could really use more rads to help it cool down, but it's limited to the 240 rad in it's loop while the other 3 rads are basically useless as their CPUs are idling.

With multiple loops, whenever one loop is idle, it's rads are more or less wasted. But in a single loop, all the rads get to work where they are needed, when they are needed.

Reasons for multiple loops

1) Eye candy
You get to have multiple reservoirs with posible multiple coolant colors. That's the only pro of a multiple loop set up. And I imagine that's not a big concern in a server environment.

Cheers
cheers.gif
 
#11 ·
Quote:
Originally Posted by PepeLapiu View Post

Reasons for a single loop

1) Cost
With a single loop, there is only one pump to buy, maybe two for power/redundancy. With multiple loops, you will need multiple pumps no matter what. More fittings to buy, multiple reservoirs.

2) Maintenance
Only one loop to build/bleed/drain/clean/monitor.

3) Noise
Less noise from a single (or dual) pump over 4 separate pumps.

4) Heat
Pumps do inject heat into your loop, a single pump won't heat up your loop as much as 4 would heat up their individual loops.

5) Safety
With multiple loops, you multiply the chances of pump failure and leaks by the amount of loops. Should one of the loops fail, it's CPU will heat up and the rig needs to be stopped. With a single loop, there are fewer chances of loop failure. And you can always add a second pump for more power and more redundancy. A pump fails and the other one keeps the show on the road.

6) Performance
Most importantly, you will get much better performance out of a single loop, especially if the CPU are unevenly loaded.. Imagine if you will 4 loops, one loop for each CPU and a 240 rad in each loop. So CPU-1 gets loaded and gets hotter while the other 3 are idling. That CPU-1 could really use more rads to help it cool down, but it's limited to the 240 rad in it's loop while the other 3 rads are basically useless as their CPUs are idling.

With multiple loops, whenever one loop is idle, it's rads are more or less wasted. But in a single loop, all the rads get to work where they are needed, when they are needed.

Reasons for multiple loops

1) Eye candy
You get to have multiple reservoirs with posible multiple coolant colors. That's the only pro of a multiple loop set up. And I imagine that's not a big concern in a server environment.

Cheers
cheers.gif
Consider that most 4 socket owners are running their loops at 100% 24/7,loop idling doesnt really get involved. People buy 4/2 CPU rigs for folding or rendering,cycles where the CPU isnt working is a fail so that a fair assumption
There is more to multiple loops other than looks,guys with 4 way SLi and multiple sockets can gain a temp advantage by separating the GPU and CPU loops from each other,Multiple smaller loops over one big loop gives your pumps better performance as they are not working as hard which in turn allows for smaller,cheaper pumps.
Leaks are not a consideration once the loop has been filled and commissioned.
A 240 rad can dissipate more heat than the CPU puts out so throwing more rad at something isnt the total answer although it will speed things up a little,remember these are stock clocked server chips,they dont push out as many watts into the water like heavy overclocking,that quad socket probably pushes out less heat than my dual socket,single loop is my choice,dual if you are planning to fill all the slots with WC workstation cards.
A D5 dumps heat into a loop but DDCs dont,they dump it airside.

My x5650s at stock tops out at 34c underwater...OCd,it rises to 64c topped out

And yes,I run a single loop
 
#12 ·
Ive got 4 7970s myself and i noticed no differance having 2 loops with 2 gpus and a single loop with 4

the temp differance between GPu 4 and GPU 1 at max load after 3 hours was maybe at best 4C, And gpu's make a crapton more heat, For simplicity go with a sinlge loop.
 
#13 ·
Quote:
Originally Posted by Rayleyne View Post

Ive got 4 7970s myself and i noticed no differance having 2 loops with 2 gpus and a single loop with 4

the temp differance between GPu 4 and GPU 1 at max load after 3 hours was maybe at best 4C, And gpu's make a crapton more heat, For simplicity go with a sinlge loop.
I find that to not to be the case for me. My gpus make a lot of heat but it's not intense like my cpu. My cpu with just the cpu at high clocks can out pace my loop easily. There's just too much intense heat in one little area. Conversely my quad gpus while they are hot, they a lot easier to coool. The same loop that cannot handle the cpu at very high clocks can handle quad 7970s clocked to the gills without going into the red zone.
 
#14 ·
Quote:
Originally Posted by tsm106 View Post

Quote:
Originally Posted by Rayleyne View Post

Ive got 4 7970s myself and i noticed no differance having 2 loops with 2 gpus and a single loop with 4

the temp differance between GPu 4 and GPU 1 at max load after 3 hours was maybe at best 4C, And gpu's make a crapton more heat, For simplicity go with a sinlge loop.
I find that to not to be the case for me. My gpus make a lot of heat but it's not intense like my cpu. My cpu with just the cpu at high clocks can out pace my loop easily. There's just too much intense heat in one little area. Conversely my quad gpus while they are hot, they a lot easier to coool. The same loop that cannot handle the cpu at very high clocks can handle quad 7970s clocked to the gills without going into the red zone.
Pretty much as i found it.
 
#15 ·
Total GPU board power (as opposed to just the GPU) can exceed most stock CPUs, but the kind of OCs people build custom loops for can cause power/heat to skyrocket. The heat actually produced from even the fastest stock part is unlikely to be much more than half as much as what many heavily OCed parts will produce. My 3930k at 4.4GHz consumes double the power and produces twice as much heat as it does at it's stock 3.2GHz, and this is on air. It's not unheard of to see 300w+ out of a watercooled, OCed, hex core.

However, if these CPUs are not going to be OCed, you probably don't need as much cooling as you think. A single 360 rad, a good pump, and four blocks in series should be fine, unless these are some exotic, extremely high TDP parts (IBM POWER chips or something). I don't think any part on C32, G34, 1366, 1356, 1567, or 2011 has a TDP over 150w.
 
#16 ·
Quote:
Originally Posted by Blameless View Post

Total GPU board power (as opposed to just the GPU) can exceed most stock CPUs, but the kind of OCs people build custom loops for can cause power/heat to skyrocket. The heat actually produced from even the fastest stock part is unlikely to be much more than half as much as what many heavily OCed parts will produce. My 3930k at 4.4GHz consumes double the power and produces twice as much heat as it does at it's stock 3.2GHz, and this is on air. It's not unheard of to see 300w+ out of a watercooled, OCed, hex core.

However, if these CPUs are not going to be OCed, you probably don't need as much cooling as you think. A single 360 rad, a good pump, and four blocks in series should be fine, unless these are some exotic, extremely high TDP parts (IBM POWER chips or something). I don't think any part on C32, G34, 1366, 1356, 1567, or 2011 has a TDP over 150w.
my x5650's are stock clocked at 2.6 and run very cool at 34c loaded,Once i hit them with the volts stick then i can squeeze 4.1 out of them but,as you say,they become little furnaces and have always been the part of my loop that I would want to separate from the rest.