Ballistix PC4000 (original 56278 P/N - Z503.16TD with Micron -5B rev D chips) were undeniably the best reaching 290-300+mhz consistently, in the right hands, at 3-3-3-8. These also had a very high failure rate and as such are incredibly rare today. Crucial brought out atleast 2 more P/N's & revisions .16TD1 & .16TD2 which seemed to improve the failure rates somewhat but were based on newer chips -5B rev G & F, I think, but were also not as strong at reaching the same OC heights, 260-290 was more realistic with these ones again at 3-3-3-8. Speculation that the failures were either PCB or SPD chip issues rather than the memory chips themselves.
Other options are Samsung UCCC, G.Skill PC4000 HZ is fairly obtainable and they regularly acheive 260-280mhz at 3-4-4-8, some examples known to get upto 300mhz. Key with these is low volts. Start as low as 2.2v and step your way up. Adata Vitesta PC4000 Extreme Edition also have a reputation of getting top clocks as far as UCCC go.
Then you have Infineon CE-5/6, Mushkin Redline XP4000 and Corsair XMS4400PRO are among the top kits with these chips IME, these chips are known not to do well at high clocks in 3D though, artifacts and crashes. For example, 285mhz which is towards the ceiling of what you can expect at 3-3-2-8 could be Prime/SPI32M stable all day long, but wont be 3D stable. Again in my experience, 3D stability is somewhere upto 10mhz lower than synthethic tests.
The XMS4400PRO across many samples I have are consistently getting upto 260mhz at 2.5-3-2-5, 270+mhz at 3-3-2-5 and 280mhz+ at 3-4-4-8 which are their rated timings. They are also the fastest and only 2GB set to be released above PC4000, so some good heritage too.
My favourite are the Ballistix (& Tracer's with the same chips)
Top tip with any 2GB set, start at low volts and step yourself up through the clock range. Start at 2.5v (2.2v with UCCC). Sub-timings are very important too, add voltage as a last resort.
