Run memtest86+ to test just your RAM. That'll tell you if the problem lies in your RAM or not.
Also, change the RAM to FSB ratio or the CPU multiplier to set it at stock speed, just to eliminate possibilities. It could very well be that your FSB can't take the high speed.
Try different things. RAM at stock with processor running fast and test it and vice versa. Might want to try to set both at stock using seperators and multipliers too, just to see if your FSB can take it.
Are you lowering your HT multiplier as you increase the FSB?
AMD Athlon 64 3000+ socket 939 @ 2.3 GHz
MSI K8N Neo2 Platinum motherboard
EVGA GeForce 6800 GT
2 GB DDR 400 (PC 3200) (2 x 1 GB sticks) (Dual Channel)
DVD player and seperate DVD RW drive
80 GB Western Digital Hard Drive
500 watt power supply
Sound Blaster Audigy
Logitech 5.1 surround sound speakers
SAMSUNG SyncMaster 710T LCD monitor
Aspire X Navigator Case