That is a wacky ratio.
Take the bus back to 200. Set multiplier to 19.5. Leave Vcore at 1.50 (does your board have a no Vdroop option? If so use it) Take your ram to proper speeds, x8 multiplier so 1600 and set the timings correct. Make sure the ram voltage is at 1.65. Take the north bridge mulitplier to 12 (for 2400mhz) and the hyper transport to 11. Bump the CPU NB voltage by .050.
Give that a shot I guess.
Huh, I dunno then man I guess you did just get a dud. It clocks like a C2!
Just got another 4870, originally wasn't planning on going crossfire, but for 100 bucks..Why not?