may i ask..............and dont take this the wrong way , but why are you overclocking the cpu on that rig? The only improvement you'll see is in benchmarks such as super pi
I think your psu may be an issue if your overclocking too it seems a bit "weak"
you MUST get aftermarket cooling you cannot oc on a stock cooler
disable C1E and EIST before you start
Dont go over 1.45 volts on the cpu voltage
Dont go any higher that 1.35v on the fsb voltage
dont let your cpu run over 71 degrees in any stress test , if ity does you have to back off the clock or the voltage
Never leave any voltage settings in bios at auto
never use any utility to overclock your cpu , use yourself and your bios

3 gig is EASY on a 6600 GO , any higher and you need to start tweaking the voltage
Make sure you keep an eye on your ram speeds as you up the fsb your ram will speed up too , either unlink the ram from the cpu or manually set the dividers so it doesnt run too fast
Use 3 gig as a starting point , boot into windows and use real temp to monitor your temps and cpu/z to monitor your voltage , it will drop when under load you need to keep an eye on this (look up vdroop)
download memtest burn the iso onto a cd and boot with it , let memtest run an hour or so to make sure your ram is stable
boot into windows
run 10 passes of intel burn test on standard settings then run prime 95 for at least 2 hours , any errors you need to up the voltage to your cpu or slacken off your ram timings a little , even if prime runs for 1 hour then craps out it still means your cpu is unstable.
the 6600 is very voltage hungry at high clocks and because its 65nm it runs quite hot , to get mine stable at 3.4 i was running 1.48v in windows 1.5 in bios (i wouldnt recommend those settings)
any overclock/overvoltage is gonna reduce the life of your cpu be aware of this
good luck

, and any app ive mentioned in there such as prime 95 can be easily googled
go here for any more advice
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