Is there such a thing as too much flow?

Well..

I am using the Danger Den TDX cpu block, but I noticed with the Eheim 1250 and 1/2" lines that my flow indicator wasn't moving as fast as I expected it to, well things were fine and temps were good.. Then I upgraded to the FX55..

Temps were definitely more volatile and I decided to pull the TDX and make sure it wasn't clogged. I soon found out that the TDX had a very restrictive plate inside with a small vertical cut through it which I'm assuming it acting as a diffuser to create some turbulence.

It was gummed up a bit so I pulled it cleaned the block which wasn't dirty but reassembled without the diffuser and it's using the copper fins as diffusion at this point. Woah.. the flow is SIGNIFICANTLY higher now and my temps almost have 0 variance under load..

So my question is since I have a high flow pump should I keep the diffuser out and use the diffuser at the base of the CPU block, or should I put it back in with the massive restriction of flow? At this point my CPU is sitting at a nice 25C, and doesn't really have much variance even under load.

my temps fluctuated a lot also...wondering the same thing

The issue was probably that the pump you're using doesn't have enough head pressure for the nozzle plate you used. If you used a less restrictive nozzle (which in essence is what you did but to a lesser degree) or upgraded your pump you would see better performance.

Eheim 1250 should be more than enough I would imagine.

Moto7451 said:

The issue was probably that the pump you're using doesn't have enough head pressure for the nozzle plate you used. If you used a less restrictive nozzle (which in essence is what you did but to a lesser degree) or upgraded your pump you would see better performance.

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silvrhand said:

Eheim 1250 should be more than enough I would imagine.

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Well not really. It has a 2M head. Pretty low by todays standards. Not a bad pump by any means, just not the most powerful. The nozzle you removed is an accelerator plate, it is there to create a jet to shoot into the base of the block. You will have better results with it in place.

The interesting thing is that my flow has considerable increased and my temps have lowered and stay lowered even under a 15 min 100% cpu test.

nikhsub1 said:

Well not really. It has a 2M head. Pretty low by todays standards. Not a bad pump by any means, just not the most powerful. The nozzle you removed is an accelerator plate, it is there to create a jet to shoot into the base of the block. You will have better results with it in place.

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It is possible that your current setup benefits having the nozzle removed. As nikhsub pointed out though, a stronger pump could yield better performance with the nozzle. Experiment a little.

The direct answer to your question is yes, there’s such a thing as too much flow. Once you reach 1.5 to 2 GPM, you can’t improve upon your cooling. With faster flow you’re just throwing heat at a problem you can’t solve.

You didn’t give much information, such as what you ambient temperature is, what kind of radiator and fan you have, what kind of processor you’re cooling, or whether you did anything else while you had the system apart, such as reroute tubing, clean dust out of the radiator, or even tried a different procedure for mounting the block.

You can look at temperature in two parts...CPU to water and water to ambient. Under load, if you have a 5 C difference between the CPU and water, you’re doing well. If you have a 3 – 5 C difference between your water temp and ambient, you’re also doing well. So under load your CPU temp could be between 8 and 11 C above ambient, at best. If it’s lower than that then something could be wrong with the software reading the sensor. But like I said, we’d need to know lots more info to make a good guesstimate at what your temps should be like.