well I seem to have got 500x7 orthos stable, thing is I cannot have those 2 settings to fast or use the 266 strapp setting.

I went ahead and flashed to the rebel haven version of the 4-24 bios also and seems to have helped.

using all the settings mentioned and 1.28 VTT and 1.45 NB volts all else stock, +.100 on the cpu and ram at 2.1.