A statement about loop order

AngryBeaver · May 17, 2021

So while I know that traditionally loop order doesn't matter... I have found that this isn't as true as it once was. Let me explain a scenario.

With the new GDDR6x cards there is a LOT of heat being pumped into both the loop and into the case via the backplate (silly hot vram). If you are like me and run multiple rads (exhaust and intake) then this next statement is very important to you.

When you setup your loop going forward make sure you are always having water flow to the exhaust radiators FIRST before flowing to the ones as intake. Other components don't matter at all, but the order of radiators DOES make for a big difference. Let me explain. Let's assume we are talking a simple 2 rad loop with one exhuast and one intake. If you flow to the intake radiator first 2 things happen. First you get access to nice cool ambient air from outside the case, but having an exhaust radiator after it just adds heat back into the loop since it is getting warmer case air. Second, you are letting the brunt of the heat get dumped into the case.

Now if you were to hit the exhaust rad first. The brunt of the heat being dumped could be outside of the case. Then when it flows to the second radiator which is getting cooler ambient air it can then see a further reduction in temp. So in the end you are killing 2 birds with one stone. You are reducing the internal temp of your case, while also making sure that the maximum amount of heat is being removed from your loop.

For me the gains were fairly noticeable with a 2c deltaT drop. I am also using a case that has good airflow (Enthoo 719) so I was actually shocked to see the effect this had.

Anyways I haven't been very active on these forums lately, but figured I would drop this message here in hopes it might help someone else.

Windows7ge · May 17, 2021

I'm skeptical about this. A 2°C drop isn't very conclusive. Even if it's true what are you going to do with that 2°C? Not a whole heck of a lot.

While technically the first rad after the heat producing components is going to be hotter than subsequent rads a high enough flow of liquid is going to spread that heat across them fairly evenly after everything hits equilibrium.

I would propose an additional test. What pump are you using? A Laning D5 such as the MCP655 has a very high flow rate with high head pressure. If you adjust the flow rate from low to high in the before mentioned "not advised" configuration this may increase the cooling performance and negate the worth of re-plumbing a loop.

AngryBeaver · May 17, 2021

13 minutes ago, Windows7ge said:

I'm skeptical about this. A 2°C drop isn't very conclusive. Even if it's true what are you going to do with that 2°C? Not a whole heck of a lot.

While technically the first rad after the heat producing components is going to be hotter than subsequent rads a high enough flow of liquid is going to spread that heat across them fairly evenly after everything hits equilibrium.

I would propose an additional test. What pump are you using? A Laning D5 such as the MCP655 has a very high flow rate with high head pressure. If you adjust the flow rate from low to high in the before mentioned "not advised" configuration this may increase the cooling performance and negate the worth of re-plumbing a loop.

I actually am using a single d5 atm and it is running at 90%. So not much if any gains to be had from flow. I think the biggest gains are the fact the exhaust rad is dumping heat before it hist the intake which is really helping keep internal temps down and thus making the other rad more effective.

So my loop order right now is Res/pump > Exhaust rad (xr7 360) > Intake rad (xr7 480) > Cpu > GPU. All I did was just flip 2 hoses to make the top exhaust rad first.

Now on to equilibrium in theory with enough flow you are right, but we still know that a rad with colder air can reduce the temp lower than one with hot air. So if you hit the hot rad after the cooler one you pose the risk of adding heat back or reducing the thermal transfer.

Anyways I am curious to see what other people have found. I am pretty confident in what I have seen, but always open to further results.