I have 80+ mods installed in Minecraft 1.5.2, Forge version 5.2.23.738. I can play Minecraft perfectly fine in 32 bit but I'm unhappy with the performance drop of using 32. But when I try to play it in 64 bit I get out of memory prem space errors. What happens is the Mojang screen will be showing and the game is loading, then it will go black screen. I check the forge log and this is what I have.
Might I add, Java 1.7.0_25 with -Xmx2048M -Xms2048M -XX:PermSize=256m -XX:MaxPermSize=512m. Also the server I created for these mods work perfect on 64 bit.