I’ve been really happy with the Promise NS4300 network attached storage (NAS). It’s biggest weakness is its noise. I got sick of it so I pulled it apart to see what I could do about it. The PSU fan was a 40x40x20 fan (model AD0412UB-C50). Here’s a spec sheet. The noise level is rated at 36.1 dBA. Finding info on the 80x80x15 case fan (model fd128015eb) was a little tougher. It’s noise level is rated at 37.5dBa.
So far, all I’ve done is put some neoprene washers to isolate the vibrations of the PSU fan and replaced the 80x80x15 with a 92x92x25 fan. I mounted the new fan on the outside of the unit. It makes it uglier, but so far it’s been much quieter. I’ll make guides on how to crack open the housing and what I did later. (Hint: you’ll need a T10 security bit)
The only thing wrong now is that the rpm sensor for the case fan isn’t working, so the unit kept beeping incessantly. I gotta find out if I messed up my fan’s rpm sensor or what. Luckily the web admin interface lets you disable the beeping.
I haven’t expanded the grill for the 92mm fan from the 80mm fan yet. After I do that, I can disable the PSU fan and duct it into the case fan. With the new fan on its lowest speed, the case is 39 deg C. With the fan on its highest speed (it’s still quieter than the old fan) it goes down to 35 deg C.