ATX PSU circuit board width

[Jacka]

I'm looking to fit some ATX PSUs along side ATX motherboards on some 1u racks, which is only possible if the width of the circuit board inside the PSU is 4mm less than the casing, i.e. <146mm.

Would anybody with an old PSU be kind enough to open it up and do a quick measurement for me?

Thank you!

[Jacka]

Gutted a few PSUs today and measured the boards.

Two were 145mm, one was 146mm.

The width of an ATX motherboard is 305mm, so minimum combined width of 450mm, which is exactly the width of the rack shelves I've sourced.

I'm not comfortable with having the PSUs completely uncovered, so was thinking of using some thin plastic to cover them.

Can anybody suggest a suitable material?