Pump / water loop performance question

[Archaic0]

Country: USA

Games, programs or workloads that it will be used for: Office work & a few games at 1440

 

Background:  I've been building a server chassis rig for a couple years now.  I've had to iterate several times as I faced challenges, mainly with temps.  I started with a 1U server chassis and while this "worked", it required a 1U CPU block, pump, and micro reservoir along with 40mm tall radiators and fans that did not keep up with any load at all.  I expanded the height above the CPU with an acrylic "bump" window to allow for a better CPU block and that solved for normal office work and low stress.  Gaming and other high stress loads would lead to throttling however in only 30 minutes.  I finally gave in and moved up to a 2U chassis, 80mm radiator and fans, and a real pump and reservoir.  This solved for all loads and everything is stable now.  I've been able to run synthetic stress tests and game for 6+ hours and temps top out at 60-70C essentially.  (gaming temp chart attached below)

 

Concern: I'm now in an optimization mode and I'm curious about my water pump and the loop because I'm not sure I'm getting the flow that I should.  My pump is an Alphacool VPP655.  The spec sheet says it will do up to 1,500 lph at 12v, but I'm only seeing about 230-260 lph as measured by two different flow meters.  (Side note, I HATE flow meters at this point, they all seem to suck very bad, at least the visual ones.)

 

I'm sure I'm impeding the water flow by some amount with flow meters and my M.2 water block, but I feel like monitoring the flow at least visually is prudent and the M.2 mounting on this motherboard makes the drive touch the heatsink for the motherboard components so before I added that my M.2 was getting to 60-70C at idle.  Still in the acceptable range, but crazy hot for just idle.  Whoever designed this board to have the M.2 drive TOUCH the motherboard heat generating components should be flogged!

 

Question: I'm mainly curious if the 230-260 lph flow is reasonable for this pump or if that number proves some huge restriction or under-performance.  I could probably remove the M.2 block (or upgrade it), but I was also wondering about adding a step-up voltage board to drive the pump at 24v since it is rated for up to 24v.  I don't know if that would cause it to run faster or not though given that it is PWM and already running at 5,000 rpm.  There may be some room for optimization in the loop path itself.  I could eliminate 3 90s by removing the M.2 block and relocating the new flow meter.  I MIGHT be able to remove 1 more 90 with some creativity around the visual flow meter.  I don't know if all that would be worth it though.  Given that I'm currently handing the heat load fine, if all I do is increase the flow by 10-20% and drop temps by 5-10C, I won't care about that.  If there is potential to double my flow rate and maybe drop 10-20C though, that might be worth some changes as I could then also put the pump on a curve instead of running it 100% like I am now.

 

Attached you'll find pictures of my setup.  Phase_5 shows an older flow meter that died (like 3 before that).  Phase_6 shows the current status with a brand new (got it today) flow meter [6] that already seems to suck because the visual fins stopped moving, but at least this one has a good flow-by design so stuck fins don't slow down the flow (at least I don't think it does).  It also shows a new non-visual "high-flow" flow meter [3] that so far is still working and giving me readings.  In the phase_6_flow image I traced the water path and marked the components of the loop.

 

Any comments or input would be appreciated!

 

[0] - Alphacool Core 100 Aurora D5/VPP pump and rez (VPP655 pump)

[1] - Corsair Hydro X Series XC7 RGB PRO CPU block

[2] - Bykski M.2 water block

[3] - Alphacool ES High Flow and temp sensor

[4] - EK Quantum Vector FE RTX 3080 D-RGB water block

[5] - Alphacool NexXxoS UT60 full copper X-Flow 80mm Quad radiator (4x80mm)

[6] - Yoidesu Meter Indicator (visual flow indicator)

 

 

 

[strange13930]

does the flow increase as the computer heats up

 

[Archaic0]

1 hour ago, strange13930 said:

does the flow increase as the computer heats up

 

No, I have the pump set to 100%, which is 5,000 RPM in this case.

 

Or are you wondering about thermal expansion of some things or the viscousness of the cooling fluid?

 

The fluid is Corsair Hydro X Series, XL8, Performance Coolant.

 

[strange13930]

I didn't know if it was like case fans and change speed with different temps

 

[Archaic0]

10 hours ago, strange13930 said:

I didn't know if it was like case fans and change speed with different temps

 

It will if I set it to a curve mode versus full speed mode, but I've currently settled into just running it full speed while I work out other things.  If I am able to improve my flow rate I may be able to set up a curve to slow the pump down during lesser loads to save some wear on the pump and drop the noise a bit.  It's pretty quiet even at full speed, but it is quieter at the lowest speeds.  Funny enough, it's super loud in the middle speed range because of harmonics with the chassis.