Nearly all, if not all of them. New PSU's come 24pin - decent ones with a 24->20pin down converter. M
Yep there are loads that are ATX 2.0 compliant but unless you give a rough budget or say what sort of system it is to power it can only be a very general recommendation. So here goes with the general part - look at Enermax, Seasonic, Tagan, FSP and Akasa