Help with OC MSI K8N Neo2 Platinum

Hi,

I've been experimenting with high memory overclocks on my K8N Neo2, and when I go above about 210 MHz, I freeze up at the BIOS screen. I determined that it is my serial ATA controller that is screwing up and if I disable SATA in the BIOS, I can push the mem speed up to 275 MHz +. Any ideas why this is happening?

I've been lowering the CPU multiple and the HT multiplier to keep things running at roughly 2.4 GHz (FX-55 standard speed), so that isn't an issue. Is it possible that my PCI lock is not working? Seems like other things would be messed up too though if this was the case.

Thanks for any insight on this one!

Timings are 2.5-4-4-10 1T

SPECS:
K8N Neo2 Platinum MB
Athlon FX-55 w/stock cooling
2x512MB ShikaXRam Dual Channel Kit (DDR550)
2x40 GB Western Digital Raptor in Raid 0
SB Audigy Platinum
GeForce6800 GT OC @ 420/1100 mem