I take it you are looking to replace the front fans?
The Akasa Apache fans will be a great improvement over the corsair. Quieter, more air flow and a higher air pressure.
I'm using these for my two front intake fans, very impressed with their performance so far. Only 29.2 dB too!
https://www.overclockers.co.uk/showproduct.php?prodid=FG-045-BX
I'm using these for my two front intake fans, very impressed with their performance so far. Only 29.2 dB too!
https://www.overclockers.co.uk/showproduct.php?prodid=FG-045-BX
At 1800RPM? I doubt it.
I like the apaches but some caveats once you start turning them up (>~1000 rpm) they aren't that different from any other quiet fan - while they will generally move more air with less noise at lower RPMs than many others even that is a bit hit and miss - I bought a load for a new build and found that IIRC something like 1/3rd weren't anything like as quiet as the other 2/3rds.
Seen these doing quite well in a few reviews recently https://www.overclockers.co.uk/showproduct.php?prodid=FG-000-PL&groupid=701&catid=2331&subcat=1816 but not tried them myself.
Why ?
Don't you like yours or find them bad?
No fan will do 29db(a) at 1800rpm, those noise figures that quoted will always be at minimum speed just to make them look good.
Here's some testing I did:
http://forums.overclockers.co.uk/showthread.php?t=18665876
Up to around 1kRPM there's not a lot in them, this is where most fans become noisy IMO, sometimes even below that (like the SP120s).
Those £4 Nexus fans spin at around 950RPM and are truly silent, I couldn't even hear them, which seemed bizarre at the time.
Would have been interesting to see below 1K RPM as well - I've found the Apaches still move a fairly decent amount of air at 600-700rpm while generally being quieter than anything else I've tried (that are still moving anything like close to the same amount of air) - whereas once you get to 1K they are give or take pretty much the same as any other good fan.