Phenom II 960T vs i5 3570k

Hello, I have a Phenom II 960T overclocked to 3.4GHz (same as 3570k), and I was wondering how much of a performance boost this processor is going to be. I have already bought the motherboard and ram to upgrade to it and I'm just waiting for my paycheck tomorrow to buy it. So you can know you're not wasting your time replying to me because I will use this information. I cannot overclock passed 3.8-3.9 GHz because my mother messed up and bought an H77 motherboard instead of a Z77 motherboard. I'm not going to put her through the trouble of returning it so I'm going to keep it until a new chipset comes out.
Thanks
Specifications
New Motherboard: ASUS P8H77-V LE
New RAM: Corsair Vengeance 8GB (2x4)
Current Motherboard: Asrock A770DE+
Current RAM: 4GB Corsair ?
Current Power Supply: CX430 from Corsair
Case: CoolerMaster 430 Elite (planning on getting a new one with a side panel if anybody can recommend one that has a black interior)
Hard Drive: 320GB one from a 7 yearold HP Pavilion (it still works great; the hard drive)
Graphics Card: XFX 6750, May get a 7870
Current Processor: Phenom II 960T Thuban/Zosma (CPU-Z says Thuban but newegg says Zosma)