A week ago, I installed Seasonic X-460 into my P183, and my observations suggest is that having separate PSU chamber is rather a disadvantage for this setup.
In X-400 review, it was mentioned that cases with bottom PSU mount may be advantageous for fanless; it seems to be true, since (in absence of significant forced airflow) hot air will go up because of convection and escaped by system fan(s) (funny that at the beginning of ATX era the PSU was responsible for overall system cooling and now it may be dependent).
However, in P183 there is a inter-chamber wall; it is not airtight but definitely impedes the airflow. Without fan in the lower chamber, it creates a closed space with little air circulation. It should be also noted that P183 lacks any holes in the bottom for air intake which some other cases have. I know it is made to accomodate their non-standard PSUs.
I removed all plastic wall components which freed quite significant openings in the wall. PSU temp seems to be notably lower now (of course it was not overheating anyway in my system which is probably is above 250W only at Prime95+Furmark).
However, what do you think will happen if someone wants to have X-460 at full load (or let's say at 400W) with P183?
Will it do just placed in lower chamber? Using lower chamber fan makes fanless PSU pointless.
Any experience of "heavier" systems with X-400/X-460? Which fan config would you use for such systems?
Using fanless PSU with 400W+ system is maybe not too good idea by itself, since other components will be not that silent anyway, so please take my question as theoretical
P.S.: The system is Phenom II X4 965 undervolted to 1.25, with S. Mugen 2 and one Noctua system fan. Video is passive Radeon 5570.