The Corsair Twin2X 6400 is the first RAM that works at low latency, high frequency, "happily sitting at 800 Mhz" and able to reach 4-4-4-12 through EPP, said Atomicmpc after testing the modules. There are lower latency DDR2 800 and 1066 RAM sticks starting to hit the streets, but they are very rare. Mushkin, Geil, OCZ and, of course, Corsair are working on that.

The system used for testing included ASUS M2N32 SLI Deluxe with an FX-62, it pulled 8936MB/s int and 8921MB/s float in SiSoft Sandra 2007. It seems nVidia has taken the fun out of overclocking too, said the guys after they were unable to push the timings any higher than those it had already specified. Mark up one for EPP.

After setting up the CPU as high as it would go, without losing stability, by setting the HTT up to 215MHz, and hence the RAM to 860MHz, the following results were obtained in Sandra: 9401MB/s int and 9338MB/s float.

Trying to get a higher clock by lowering the multiplier and raising the HTT even more resulted in instability according to Stress Prime 2004, so the RAM timings were put to the SPD default of 5-5-5-18, and consequently hit 1155MHz thanks to an HTT of 231MHz. Unfortunately, this couldn't overcome the latency increase, and the loss was around 400MHz of bandwidth according to Sandra.

The specs are:
DDR 2;
800 Mhz;
5-5-5-18 by SPD;
4-4-4-12 by EPP.

The price is $460 for a kit with 2 x 1024 MB modules. It scored an 8 out of 10, so you might want to wait a little longer to see what else is good these days.