oc the ram can be done in BIOS. viewing the temp need a sensor probe though.

by the way, how much can the KVR chip 512MB DDR400 can be oc'ed? tried at 3-4-4-8 @ 220MHz with 3-3-3-8@ 210MHz both at 2.7V the difference not that much? is it lose the timing greatly affect my speed even though at higher clock rate?

So you're starting up just like me a few months back 

1) Go to LYN RAM handbook and read it thoroughly.
2) Go to your BIOS and set the timing according lowering the timings one notch at a time.
3) If it fails.. perhaps to boot or it keeps restarting your PC, increase the voltage by a lil but don't go too high.
4) I guess when you've reached your limit, thats the best your RAM can go.

But bear in mind, having tighter timings will decrease your RAM Speed limits (in Mhz), thus it makes overclocking your processor improper because supposedly you are to sync the FSB with RAM speed at a 1:1 ratio.