G.Skills 6400HZ if the current stocks have as good chips as the old stuff...
currently on 1200 5-5-5-18 @ 2.3v and it goes upto 1248 memtest stable on those timings and voltage so I could probably drop either the timings or voltage a little and keep 1200MHz. In testing I've got over 1300 perfectly stable with enough voltage but I wouldn't personally run them over 2.3 for long term useage tho people say upto 2.4 is fine. On 4-4-4-10 you can get them to 1066 with 2.3 volts tho I had to go to 4-4-4-15 to get them stable at 1000 on 2.2 volts.
For a comparison using Everest Memory Read Benchmark
1000 4-4-4- = ~9800MB/s
1066 4-4-4- = ~10,000MB/s
1200 5-5-5- = ~10,200MB/s (oops)
Thats with an E6600 @ 3.5gig