Water Pressure & Flow Rate

Howdy there,

New comer here, and I would like to seek the advice of the community about some questions I had about waterloop setup. I'm re-doing my waterloop after my pump died on me, and I was curious about 2 things.

#1 - Does it matter if you setup your pump to push water up or down, or is it irrelevant?

What I mean by this is that obviously the GPU waterblock is below the CPU waterblock, does it mater if the pump output goes through the card first, and then the CPU? I'm wondering this not for heat because I understand that in a closed loop the heat will even out, but more about which option, if any, gives better flow performance?

#2 - Is the overall flow rate of a water loop determined by the component with the lowest flow rate?

I'm almost sure it is, but I can't really find anything about this specific subject so I was curious what you fine people could provide in terms of insight.

I hope I'm posting this in the right section, new comer here.

Thanks in advance,

It all returns to the same location. It either goes up on the way out and down on the return or down on the way out and up in return.

Good question on flow rate. My take is this....closed loop so flow flow rate should be the same throughout? I imagine only pressure to change. if it's 1.5 gpm going out, doesn't 1.5 gpm have to go in? If not wouldn't it run dry? Speeds/pressure may increase in bottlenecks like blocks, but once it comes out of that barb to your tubing, it slows back down and pressure drops.

Again, my take... someone confirm or correct the flow rate please.

to OCFs.

What I do when it comes to my loop's flow efficiency is setup a flow meter at the IN to the reservoir which is the last place it hits right before returning to the pump. That's how I measure mine and I assume most would do so as its the last point of the loop before returning instantly inside the reservoir and straight to the pump.

As far as loop configuration, it doesn't really matter as long as the reservoir is flowing to the pump. I personally like having the flow hit the CPU block first and than the GPU since the GPU can handle better Delta-Temps and heat better than the more sensitive CPU. You might shed a few degrees by doing so but not guaranteed. I have done it both ways and noticed a few degrees were shed but that could also mean I had better contact as well so I believe its a personal preference if anything.

MedievalNerd said:

#1 - Does it matter if you setup your pump to push water up or down, or is it irrelevant?

Click to expand...

Its irrelevant as its a closed loop, so while some water is being pushed 'up' so to speak, other amounts of water are going down.

MedievalNerd said:

#2 - Is the overall flow rate of a water loop determined by the component with the lowest flow rate?

Click to expand...

Not quite.... Overall flow rate is affected by all restrictions (not just the one with the highest restriction ie lowest flow rate) so you need to take into account all the restrictions formed by all your blocks, rads, reservoirs, fittings etc and add them together.

Generally we only bother with blocks and rads most of the time as these form the majority of restriction for most loops and therefore affect your flow rate the most.


Take a look at Martins website over here for some great info on these topics.... https://martinsliquidlab.wordpress.com

Wow! Thank you very much for the quick feedback, here I was wondering if my thread would just slip into oblivion. How did I even dare?

OK, so pump output up/down has no bearing, makes sense as you've explained.

And thanks for the clarification about flow rate restrictions!

If I have any other WC questions I'll make sure to come here, you people are awesome!

Cheers,