Yep OCZ has odd things like that... For example my OCZ Platinum / Fatal1ty RAM is rated at DDR2 800, 5-4-4-18 but CPU-Z reports 5-4-4-15 timings. Note that at those timings my computer fails Linpack / Prime blend with 4 sticks installed
so I'm running 6-5-5-18 instead. Did you try forcing 7-7-7-20 in BIOS to see if it is stable then?