The 870 I posted will work with 1600 RAM, you'll just have to set timings and voltage (depending on what DDR3 RAM you get) in it's BIOS. It's a budget motherboard compared to a 890FX without 16x/16x or even 8x/8x gaming capabilities. It's 16x/4x, but since it uses the new AM3+ socket it can be used with the upcoming Bulldozer CPUs from AMD. The new AM3+ sockets will work with all AM3 CPUs and will be compatible with the next generation of AMD CPUs.
Here's a roundup review of the 870 motherboards, it's a bit dated, but should give you a good idea about capabilities of the platform.http://www.xbitlabs.com/articles/mainboards/display/amd-870-roundup.html