The safest bet for 32GB is a 4x8GB, I like the Mushkin Enhanced Blackline 32GB (4 x 8GB) DDR3 1600 Model 994055 CAS 11-11-11-27 @ 1.50v - /edit link http://www.newegg.com/Product/Product.aspx?Item=N82E16820226317
VCCSA (I find it very funny from G.SKILL's Admin) - http://www.gskill.us/forum/showthread.php?p=56501"In addition for long term CPU lifespan and reduction of draw and heat considerations VCCSA and VTT value of 1.100 are advised. When exceeding 1600 speeds 1.150 to 1.200 may be required for 1866+ it is strongly advised you attempt lower operating voltage levels first and if all possible maintain 1.100 as your maximum. Considerations for defining and maintain a 1.200 can be considered but are still under analysis currently ASUS has reached frequencies in excess of 2800 in full 8 DIMM population when the quality of the IMC is high. Highest DRAM scaling has been achieved with 1.300 to 1.400 with currently no signs of issues until more analysis is completed though it is still only advised to use up to a maximum of 1.200v with an ideal recommendation for 1.100."
I've determined a VCCSA >1.35v will permanently degrade the SB-E CPU, and ditto with a VCore >1.55v regardless of CPU temps.