I tested a Second Generation Sandy Bridge (i7 2600) and a 3rd Generation Ivy Bridge (i7 3770T). In both cases they worked out of the box, like all Intel CPUs.
In the 12.04, which uses the 3.2 kernel, many performance improvements were backported from 3.3 back to 3.2 to use in 12.04. So both Sandy and Ivy should work nicely. There are even more enhancements for both architectures that we will find in the upcoming 12.10 which will benefit even more this type of hardware.
If you want to see if the CPU is correctly handled a simple command would be:
cat /proc/cpuinfo this will give you ALL the information about the CPU. Since it is a multi-core CPU, you will see a lot of information. Other ways are
sudo lshw -c cpu and
sudo dmidecode -t processor.