be carful with low noise fan. this is the only for cooling the wohle machine.
and this machine is a bit stuffed, so... check the debit against the original "airplane noise" fan
the original fan is given for 32 cfm and 28 db at 2450 rpm.
personnaly, i replace them with the noctua nf-r8 redux 1800 rpm.
they give 31 cfm for 17,1 db.
it's not silence, but it far less louder