Upgrade to sandy? worth it?

No not worth it, and you mean "upgrading" to ivybridge.
There's no performance loss by using the pcie 2.0 vs pcie 3.0

E.g : http://www.hardocp.com/images/articles/1341219566Ew8yr7...

Yeah sorry i always get both mixed up.

Ok just wondering, i tried running Hitman absolution on Ultra and the FPS was around 25-30, when i turned the SSAO to medium and the reflection to medium its was better, kinda bother me a bit that i cant Max it out

Do you have the latest nvidia drivers ? and what's your psu ?

Yes i do very latest.

Full pc specs

PSU XFX Black Edition XPS-850W-BES 850W ATX12V 80 PLUS SILVER Certified

EVGA 670 2GB

I5 2500k OC to 4.5 stable

CORSAIR Vengeance 8GB running at 1600

Windowns 7 64bit

COOLER MASTER RR-H612-20PK-R3 120mm Sleeve with 6 Heat Pipes Hyper 612 PWM, with 2 fans

I should be able to run any game on Ultra unless i did something wrong. COD BO2 also runs a lil weird when it comes to reflections

No it isn't worth it to upgrade from an Intel® Core™ i5-2500K to Intel Core i5-3570K for PCI-E 3.0 since nothing out there is using PCI-E 3.0. And yes you should be able to run at ultra wih your system.

I don't see any bottleneck or throttling with those components.
You should get about 46 fps with hitman :
http://www.guru3d.com/articles_pages/hitman_absolution_...

Check if you have the 310.64 beta drivers, and if the games in question are updated to the most recent version.
Try also some oc on the card and check the temperatures..