gunslinger_001 :
My system sometimes restarts after booting into windows or won't even boot.
I'm just increasing the multiplier from bios.I'm using stock AMD cooler.
ASUS M2N68AMSE2 mobo
Zotac 9600gt 1gb
2 GB Ram
OK, just so you know, with the stock cooler, you won't get very far with your OC. I strongly recommend you upgrade to an aftermarket cooler. Moving on...
Start your OC by disabling C n' Q, and any other power saving features your mobo has. Next manually configure your RAM settings to what is shown on the stickers or the packaging; all other voltages and frequencies in the BIOS should be left on their default values or [Auto]. You will need adjust these later.
Continue your OC process by raising the multi by .5 each time. After each increase, save and exit (F10), and then see if you can get into Windows. Repeat this until you cannot get into Windows. I realize you've already experienced, but for the sake of clarity, I'm explaining the whole process (just in case you missed a step).
WARNING! Without an aftermarket cooler, continuing from this point can be potentially fatal to your CPU.
Now that you've found the multi that won't allow you to boot into Windows, it's time to start raising your Vcore. To avoid permanent damage to your CPU, make your increases to vcore by one step incriments. After each increase, hit F10 and see if you can get into Windows. Continue this step until either:
1. You successfully boot into Windows; or
2. You reach the max CPU voltage (hint: check AMDs website for the max voltage)
That takes care of the basics. If you want to continue pushing your OC, you may need to start lowering the multi or frequency of the NB. You may also need to lower the RAM frequency; or even loosen the timings.
Once you've established the max multi, start raising the reference clock (A.K.A. FSB) by 5 MHz increments, F10, and see about booting into Windows.