NOOOOOOOOOOOOOOO dont get A-DATA ... My cousins Acer from Fry's uses A-DATA PSU and RAM , and system has given problems from the outset... hes scared but finally got courage to soon do a clean format after he prepares backs his stuff up.
A-DATA is a cheap chinese company.
YEEEEEEEEESSSSSSSSSSSS get Corshair RAM because they are a good company alto I know I spelled it wrong. More trust worthy, quality company. You be assured its not a cheap component and it will work for years and not die or give you errors.
Trust me this Acer comp is Q8300 @ 2.6 but I went over to OC his Acer lol rig,, and the bios doesnt even have any options. NO OPTIONS. its a Acer motherboard and the BIOS for real had no options for anything. Soo poor guy is stuck with 2.6 when that chip can go stock voltage @ 3.4Ghz I'm sure. He says his system is really slow can be the changing of GTS250 to 9800GT and the cheap A-DATA PSU which was 430. Probably its single 12v rail doesn't even give out proper voltages which explains his problems lol. ANyhow bottom line get Corsiar because you can be asshured that you can OC the timings a tad bit. As good if not better then your current 6400 RAM No need for that 18, you should be fine with 15 or maybe less.