Replacing the fan in ReadyNAS Duo - possible?

Fetsy wrote:

I replaced the stock fan today with this fan: http://silenx.com/ixtremaprofans.asp?sku=ixp-34-16 The silenX fans aren't exactly famous for pushing lots of air, but in exchange for a bit hotter disk I now have a quiet NAS. I have one 1TB Samsung disk that with the stock fan kept a stable 32°c. With the SilenX fan, on minimum 2000RPM, it keeps a stable 36°c . This fan seems to handle the job well when there is only one disk inside the cabinet, but I am not sure whether it would provide enough air to cool two disks down. Has anyone tried using a Papst fan?

Spring is here in Paris and temps are raising... 8)
And I've decided to make the move and switch from the stock Fan to the SilenX. No more noisy ReadyNAS Duos but very bad idea : I'm getting almost a +10°C on previous HDD temps, cruising very close to max Ambient Operationnal temps specified by HDD manufacturers (60°C). 2 HHDs per Duos, see my signature.
Equivalent or better CFM is a must have!