I couldn't find an inline temperature sensor and fan controller, that isn't motherboard dependent or requires a big front panel, but if have a recommendation of such a thing that would be ideal. Have the fan down very low (or off) and set it to step up when it warms up.
I can't authoritatively actually check with disconnecting the 52v as I've got no other way of powering the cameras. But it would take away a lot of the convenience of the hikvision boxes in that they have the Powered PoE switch internally. But I think *probably* yes, you could use one or more...
They are horribly noisy, I ended up with a new fan, and two silent power brick power supplies to solve the problem
Noisy fan hikvision NVR solved with silent power bricks
They are horribly noisy, I ended up with a new fan, and two silent power brick power supplies to solve the problem
Noisy fan hikvision NVR solved with silent power bricks
Like many other threads on here, I found my new DS-7608NI-K2-8P unbearably loud. It has a channel well technologies PSU (KSA-180S2) with a 12v 5A rail, a 52v 2.5A rail and a really noisy 40mm fan, and then a second not-quite-as-noisy 40mm fan on the case.
Everyone has a different sensitivity...