Hikvision ds-7608ni-i2 fan replaced

[Vauxfan]

I did the main fan swap to noctura but the unit is quite loud still, but it appears the noise is the side fan. And as said by others it's when the lid goes on.
If I put my hand over the side fan then the unit is silent. The notura fan makes no noise in comparison. Other than having the lid lifted off. Is the noise due to the holes where the fan is? Could I cut the grill out and mesh the hole left behind? Would that make it quieter

 

[JB1970]

I did the main fan swap to noctura but the unit is quite loud still, but it appears the noise is the side fan. And as said by others it's when the lid goes on.
If I put my hand over the side fan then the unit is silent. The notura fan makes no noise in comparison. Other than having the lid lifted off. Is the noise due to the holes where the fan is? Could I cut the grill out and mesh the hole left behind? Would that make it quieter

Was that me who said that? - I'm sure we spoke about this before!

It's far quieter when it's in the cupboard or loft

 

[Vauxfan]

It probably was you. Just wondered if it is the metal grill next to the fan that made the noise.

 

[JB1970]

It probably was you. Just wondered if it is the metal grill next to the fan that made the noise.

It's just the airflow through the holes that increases the noise of the fan itself. You could cut away the case and replace it with mesh but it might not make much difference - the mesh will still cause a disruption to the airflow and therefore increase the (apparent) noise of the fan.