Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

Hey! As you've heard, there's this buy going on over at XS. And I'm thinking of purchasing either an Iwaki RD-20 or RD-30. However, my main concern is noise. I need everything to be really silent and quiet (that's why I'm going WC). So what pump would be the better choice for silence, RD-20 or RD-30? (Feel free to undervolt both etc.) Or should I be looking at another pump altogether?

This will (probably) be the loop: Restrictive (impignent) CPU block, 2xGPU block (Maze4?), PA120.3. Maybe something else. Thanks!
~ Kris

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

If you're looking for really low noise, neither of these pumps is the answer - instead target a lower powered pump with less restrictive waterblocks (Swiftech 6000 series used to be my favorite for this, dunno about their new one).
If you want to lower your temps to match what an impingement block can do, instead focus on a larger radiator (or radiators). If you get the coolant temp down closer to ambient, you don't need to have as low a c/w block and can still have good die temps.
If you're not overclocking, it doesn't really matter, so long as you keep everything withing spec'ed operating temps.

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

None knows which is more silent of the two (when they're both undervolted to give the same performance)? :(

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

How do you plan to undervolt these AC pumps?
If you're going for silence you won't have fans @ 12v so performance is a compromise anyway.
I love the MCP350: small, silent, powerful but also recommend the smaller Eheim 1048...

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

Try two 10W MCP-350/DDC's in series with the his inlet mod if you really want a lot of silent pump. http://systemcooling.com/mcp350_mod-01.html

Beware the 18W DDC-Plus, though, as we haven't seen accoustic specs on it or even a breif review from someone who has a silent system.

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

Well.. I ended up buying one of each (one RD-20 and one RD-30). So I'll decide myself whatever fits my purposes the best.

Re: Iwaki RD-20 or RD-30 for SILENT water-cooling?
 

The RD-20 will be better suited for you since it still supplies plenty of head pressure but dumps far less heat into the loop.