I don't know about the current Z8 line, but the Z800, Z820, and Z840 all have a 3 zone cooling design. the PSU has it's own dedicated cooling channel where it pulls fresh air in from the front through the PSU and out the back. The CPU/RAM has their own zone, and the HDD/PCIe cards have the 3rd zone. It's a bit like the old DEC Alpha personal workstation design... if anyone is familiar LOLI know my z420, it seems like the optional memory shroud which pushed heat through the power supply would have caused the same issue. Mine doesn't have that optional shroud, but if the z800 is as fully baffled as the current z8 line, I would think maybe that might be a strong contributor.