Laing D5 noise and speed adjustment

[TMonte]

Hi,

I've done a few searches in trying to find threads with this information, but none seem to specifically address what I'm after. If there are and I missed them, sorry.

I just finished my first new liquid cooling system in about 4 years (see HERE). If you look closely in the foreground of the pic in that thread, I'm using a hobby grade AC/DC power supply to run the pump while I bleed the system and leak test.

Here's the issue. The D5 is set to #5 speed setting. The power supply in use pushes 13.4v, so I know the pump is spinning a bit faster than it will when using the PC's power supply (probably 11.9-12.2v). Right now it has a very slight, but extremely irritating high-pitched "whine" to it. If it doesn't go away at ~12v, what setting is the "point of diminishing return" where the decrease in noise via reduced RPM starts to create an impact in performance? 4? 3? 2?

I've read that the D5's are pretty well silent at the lower settings, but I don't want to go too low. I know the Storm design still performs very well at lower flow, but I also know it performs best with more flow and pressure.

Before anyone says the undersized radiator could impact performance more anyway, I already know that too.


Thanks!!!

Tom

[bigben2k]

Originally Posted by TMonte

...what setting is the "point of diminishing return" where the decrease in noise via reduced RPM starts to create an impact in performance? ...

If you review the chart for both Storm blocks reviewed:
http://www.procooling.com/index.php?...icles&disp=131

You'll find that the return diminishes linearly, between 1.0 and 0.5 gpm.

I say don't worry about it, and make it pleasant to the ear. Priorities. If you're lucky, the noise will disappear when you switch to a 12 volt supply.

[TMonte]

Hi bigben,

Interesting. I did some more digging after you pointed me to that graph, and found that the measured flow through the Swiftech G4 with an MCP655 (aka D5 as you know) was 87GPH or 1.45GPM using 12v, at setting 5.

So...I did some rough math and came up with this, which seems to jive with the ProCooling graph:

S  RPM    Est. flow rate (GPM)
1: 1800   0.53
2: 2550   0.76
3: 3300   0.99
4: 4050   1.22
5: 4800   1.45

(RPM figures assume the pot control is linear, min & max figures are from published data)

Which means the difference between 3 and 5 @ 12v is approximately 0.75C, according to the ProCooling data.


Thanks! That helped a lot! I figure a ~40% drop in RPM from where I am now (calculated as ~5300 RPM @ 13.4v) should net a large drop in noise and still deliver excellent performance. We'll see how it works in the real world.

I'm excited.


Tom

[Dr_Strangelove]

Hmm...any reason why you cannot run the pumo off 12V? I have this pump now and it is virtually silent on the highest setting.

[TMonte]

The pump will be @ 12v when I connect it to the PC's power supply. Right now I'm using an external supply so I can run the pump and fan with nothing else on. I know I could have disconnected everything else and run it from the PS in the box using the green wire trick, but this was easier.

It'll be hooked up tonight and running. The circuit is about 99% bled.


Tom

[Dr_Strangelove]

I would not worry too much in that case as the pump is silent to my ears even at full blast setting if run at 12V. I think the reason you are hearing the high pitched hum is that it is running above spec.

Also, sometimes the hum can come from the way it is mounted.

[TMonte]

Great, thanks for the info! It's not actually above spec now (operating range is 6-14v), and I realize the nominal operating voltage is 12.

I'll find out tonight. The vibrations don't seem to be a problem since I have it on the neoprene pad...


Thanks again,
Tom