800mhz ram vs 1066mhz ram?

Ive got 4 gigs of 800mhz ram in my rig now but i found a great deal on 1066 ram. So i was wondering how much performance increase do i get from the switch?

I have a Quad phenom 9650 overclocked to 2.5 in my system dont know whether that should effect my decision or not.

Nah, it's not really worth it. Stick with your 800mhz ram. 1066mhz ram is usually just 800mhz ram overclocked.Maximus43

Yes this is true. My ocz platinum 1066 ram was basicly that. When it runs at 1066 I can't oc my e8400 past 3.1ghz. When it's at 800 I got it to 3.8-3.9 ghz, but decided to go at 3.6 just because of more stability.