The 965 would be better for gaming, no doubts there. The benchmarks on Tom's and other tech sites confirm this. If you do a lot of video editing/conversion, graphic design, ray tracing or similar work, a hexacore would be of more benefit.
The other consideration is that your motherboard may not support the 1055T, although I assume you checked this.
Yes, based on tests performed since the launch the X4 965 is a better gamer than the 2.8 Ghz hexacore. The 1055T is better for multitasking, and I understand it is quite an overclocker although it seems you are more interested in stock clock speed.
Also, core scaling tests performed by tom's and others show that many modern games take advantage of 3 cores, 4 cores less so. I doubt any games use 6 cores effectively (or at all) at this point. I imagine they will in a year or so, but that all depends on the developers.
I'm about to upgrade my CPU, and I want to know if a quad core 3.4 ghz would run more efficiently for games over a 2.8 hexacore
This is a gaming rig that I have. And I didn't think a game would be able to take advantage of all 6 cores, and since it's at a lowered speed, would it have a less of a positive effect? thanks
If you're not planning on overclocking either CPU the X4 965 would be a safe bet for you. It'll be cheaper and provide you with pretty much all the power you'll need for today's games. I wouldn't advise that you get the X6 1055T unless you're looking to do a lot of video encoding or you're not planning on upgrading your processor for the next 4 years. Even then, you might want to consider getting the X4 965 with a decent mobo and dropping in a bulldozer processor down the road. It's really up to you.