Depending on which Asus motherboard you have they can run unstable at lower latencies.
My Asus A7N8X-E-Deluxe only lets my memory run at 2.5-3-3-6 if the frequency is 195MHz. Hopefully Asus will release a new BIOS that corrects this issue.
nForce2 chipsets are renowned for being tight of CAS latencies.
[size=0.5]Full Aluminium ThermalTake Case
AMD Athlon XP 3200+ *400 FSB* Barton (2.2GHz)
ThermalTake Volcano 11+ Xaser Edition Air Cooling
1024MB Corsair TwinX XMS 3200 (Dual Channel 2x512) 2-3-2-6
256Mb XFX 7800 GS EXTREME
2x WD Raptors (10krpm 8MB Cache) 36.7GB using RAID -0
Video Logic SonicXplosion 5.1 Soundcard[/size]