ASUS Intel 915/925/945/955 chipset overclocking

I have a P5LD2 Deluxe mobo with 945P chipset. Here is what happens when I raise my fsb to certain levels when restarting my PC.

Till 243mhz FSB - Mobo reboots like normal

243-255mhz FSB - Mobo will power off few seconds then power on back by itself

From 255mhz FSB - Mobo will power off completely. I have to power it on back manually.

I'm currently at 270mhz FSB Orthos stable but annoyed with the restart problems. I have mailed to ASUS tech support and they told me it's normal for Intel 915/925/945 and 955 chipsets to behave like this when oc too much. It seems that Intel limits oc on their chipsets. I have seen cases with mobo shutting down and power on back automaticallly but not complete power off. My mobo will power off completely after 255mhz FSB. Is it normal or something is wrong?

If it's turning back on and passing Othros I wouldn't be alarmed. My P5B does the 2nd option you have listed there. Intel is weird.