Most of the AM3+ boards I have seen can do 32gb.

Quote - 4 x DIMM, Max. 32GB, DDR3 2133 (O.C.) / 1866 / 1600 / 1333 / 1066 Hz Non-ECC, Un-buffered Memory
Dual Channel Memory Architecture

That's an average spec quote.  RAM type may vary a bit. So that's 4 x 8gb ram sticks.

The 1366 boards are 24gb with 6 slots but the new 1155 boards are 32gb with 4 slots, same as the am3+.