I solved my noisy Vegas
I started off with some fan cowls made from a 4" cardboard tube and duct tape. They dropped the noise level considerably on their own. Then, I used the same tube through a 4" hole in the ceiling to get nice cold air from the loft. Finally, I joined them all together with some flexible aluminium ducting held together with aluminium tape and job's a good 'un.
The Vegas are now running at 65° with a fan speed of <2000rpm compared to 3000rpm before, and the ambient noise level in the room has dropped from 60dB to just 38! For reference, that's a from a busy office to quieter than the living room with the TV on. The rx580s keep turning their fans off completely as the temperature in the airing cupboard is barely higher than ambient now.
Pretty pleased with that
