It's very much replaceable!
To be exact, it's a 4 pin Delta BFB0712H, also used in some G5 iMacs. There appears to be a few out on ebay that look pretty much like an exact fit despite being slightly different in color/case.
The good news is that it's mounted on rubber standoffs, and if you pull on it hard, the standoffs will pop and the fan will come out. Yes, you can pull it sorta towards you, and sorta towards the front of the case. Just be careful not to break the ribbon cable (and make sure it's disconnected!)
You don't need to pull the module out. That's such a pain in the butt!
In my case, I was U3/Memory controller heatsink temps skyrocketing up to 75c! Since I haven't yet found a fan I want I just stuck an 80mm antec in its place and have the old one hanging (delicately, I don't think it's going to rip the connector off the board this way) so that it doesn't cause fan failure messages and shut the machine off.
Actually, can you outright unplug the fan without causing the machine to shut off? Not sure.
Anyway, with the Antec - a fan that's not SUPPOSED to be there (I haven't got it ducted properly even!) the temperatures are slightly more sane. 60c now. (my CPU sensors are at 50c at the moment), even a severe beating only gets it up to 64c... a vast improvement ^_^
I highly suggest that!
Please excuse the oddness, I haven't yet purchased a SATA drive so I have an old ATA drive sitting upside down in the optical bay and a fanbus unit controlling my 3 pin antec since I don't have a 3->4 pin adaptor for it lol. Oops?
To be exact, it's a 4 pin Delta BFB0712H, also used in some G5 iMacs. There appears to be a few out on ebay that look pretty much like an exact fit despite being slightly different in color/case.
The good news is that it's mounted on rubber standoffs, and if you pull on it hard, the standoffs will pop and the fan will come out. Yes, you can pull it sorta towards you, and sorta towards the front of the case. Just be careful not to break the ribbon cable (and make sure it's disconnected!)
You don't need to pull the module out. That's such a pain in the butt!
In my case, I was U3/Memory controller heatsink temps skyrocketing up to 75c! Since I haven't yet found a fan I want I just stuck an 80mm antec in its place and have the old one hanging (delicately, I don't think it's going to rip the connector off the board this way) so that it doesn't cause fan failure messages and shut the machine off.
Actually, can you outright unplug the fan without causing the machine to shut off? Not sure.
Anyway, with the Antec - a fan that's not SUPPOSED to be there (I haven't got it ducted properly even!) the temperatures are slightly more sane. 60c now. (my CPU sensors are at 50c at the moment), even a severe beating only gets it up to 64c... a vast improvement ^_^
I highly suggest that!

Please excuse the oddness, I haven't yet purchased a SATA drive so I have an old ATA drive sitting upside down in the optical bay and a fanbus unit controlling my 3 pin antec since I don't have a 3->4 pin adaptor for it lol. Oops?