Hello,
I would burn in processor for a couple of weeks first, before OC'ing it especially if it's still under warranty !
Reason make sure it runs stable for two weeks, or 1 week BUT DO NOT turn the system off, just the monitor if you want to save on energy.
Silcon semiconductors, when they are new need to go through a burn-in process, or worked in. Just from building over a 1000 systems, and repairing allot of peoples systems, found that a burn-in is like quality control, then start tweaking the CPU, and system board out after you know for sure, and monitor the temps onboard chipset, PLL, and CPU at different times. Sometimes on the Asus boards the PLL's get really hot , and if you touch it, and you can't hold your finger on it then it's getting to hot, also try not to get the PCI bus freq 38-40 MHz. Now your going way over clocking with your sound, network, modem, and controllers, and you can fry them too (stay 33 - 35MHz to be safe).
Later KingShip
Added note check the OPN on the Athlon processor to see if the last letter ends in with a "c", or a "d". C= 266MHz FSB, and D= 333MHz FSB