Quiet PSU for 3U Rack Chassis?

I recently put my DAW in a Circotech Leopard 3U rack chassis for portability.

The fan in the Leopard's stock PSU is way too loud for DAW use, so I figured I'd upgrade. But, from what I can tell (Google, etc) there aren't many 3U PSUs out there, much less quiet ones with at least 400W.

I noticed that the Circotech case is the same one used by Spectral for their dedicated DAW PCs, which are quieter than my "roll your own" machine. Unfortunately, Spectral won't tell me who their supplier is (can't blame them, I suppose), and they don't sell their PSUs individually.

I contacted Circotech to see what they recommend, but they didn't respond.

Anyone using a 3U PSU that fits the bill?

Thanks,

JC