ASUS, the worldwide leader in motherboard design and sales, today announced the release of the industry's first AM3+ CPU enabled motherboard solution based on the existing AMD 8-Series Chipsets. Current owners of an AM3-based board* will make their AMD 8-Series motherboards compatible with the latest AM3+ CPUs with a simple BIOS** update from the official ASUS website.
BIOS Upgradable Supported AM3 models
Crosshair IV Extreme
Crosshair IV Formula
Upcoming ASUS M5A Series models (AM3+ socket with AMD 8-series chipsets)
Granted, it's a Micro-ATX board, but can FX support more than two measly RAM slots?
I don't think that has anything to do with the processor
That is a product of the motherboard itself (which reports max ram of 8GB, or 2x4GB). Most important, it notes DDR3 1866MHz support -- the IMC of BD-Z is purportedly 1866MHz stock.
I suspect dual-channel MBs with 4 DIMM slots at a minimum would support 16GB of RAMs, or 4x4GB. If you wish to go beyond that I imagine there are vendors/OEMs who would be more than happy to have you as a customer (I suspect 8GB sticks and motherboards might be a bit pricey )