Reconsider the Seasonic G360. While it only has one PCIe 6/8 connector(correction, 6pin only
) (by PSU standards it's not allowed to sport two 6's even if one 8 can deliver enough power for any dual-6 card), it's a perfect size for smaller builds, have excellent quality and runs quietly for an always-on fan. With an adapter for a second 6pin PCIe the G360 can power more powerful systems like if you upgrade to a GTX 670 card without issues. I wonder if anyone is putting out an 8pin PCIe to dual 6pin adapter. Someone should, even if I suspect it's not ATX-standard kosher. Edit
: Oh I didn't realise the G360 only has a 6-pin and not a 6+2-pin PCIe connector. Hardly anything uses the 8-pin configuration, but still. Got my own today and am admiring its features before I install it in an ITX build tomorrow.