@DamienKC: I have about the same problem, VX works fine (but however, one crash every three days?!) but the old OCZ tccd 431 memtests at 300+ and cannot boot into windows at high speeds... (tried about every bios that is optimised for X2, no difference).

So I don't suspect the memory and I hope it's not the cpu (never used the faulty 704-2). On monday I will try to clear the c-mos-chip on a Galep-4 and program the 704-2BT back in it... Hope this solves this crazy problem...
I'll tell you about the result and I'm confident the G.Skill you bought is not faulty.