New pc Frame lag (Help Please)

[harrypcgames]

So yesturday i built my first gaming pc. I was and have been playing csgo on it pretty much since i got it, I've been playing it at max settings no problem with 90+ fps and no sutter. But suddenly the next game i played i was getting alot of frame suttering and alot lower average frame rates ,Lower than 60. When i look at cpuz i see that my cpu is dropping to 799Mhz and back up to 3.2 constantly, could this be a problem?. I've no idea what the problem is here but it would be nice if somone could help me figure this out. thanks,

Also it's even causing massive lag in games such as minecraft so there must be somthing wrong here.

Build:
Intel pentium g3258 3.2ghz (stock cooler)
gtx 650
asus H81M-PLUS motherboard
8Gb corsair beast ram
Corsair Vs550Watt PSU
Windows 7 Home Premium
Could it be that i've had it on for too long and it's over heating or what?

Please help me asap.

-Thank you.

 

[Forever Oleg]

Download Speccy and look at the temps