The effect of memory speed on AMD Trinity APUs
 

In order to find out exactly what the influence of RAM speed is on AMD processors, we put an AMD A10 5800K processor on an ASUS F2A85-V Pro motherboard and ran a number of benchmarks at various memory speeds.


The performance differences for 3D benchmarks and games, which really tax the integrated GPU, are significant. In 3DMark 11, DDR3-1866 offers almost a 12% increase in performance. In 3DMark Fire Strike it's almost 18%. In games it's even more, more than 20% in Tomb Raider, almost 25% in BioShock and Dirt and almost 30% in Hitman Absolution.

Those significant differences are limited to games, however. In CPU benchmarks like Cinebench and the TechArp x264 video encoding test it's negligible.

http://us.hardware.info/reviews/4372...d-trinity-apus

Cheapest DDR3-1333 at Newegg.com is $18/2gb stick
so building an 8gb setup would cost you $72

Cheapest DDR3-1866 kit at Newegg.com is $38/4gb kit (or $19/2gb stick)
8gb system would cost you $76


in short: go for highest rated DDR3 sticks if planning to use the integrated graphics on AMD systems. price difference between 1333 <> 1866 is negligible!