Ivy Bridge processors are Intel's 3rd generation Core i3/i5/i7 microprocessors and the first chip to use Intel's 22nm 3D tri-gate transistor technology, allowing more than 50% power reduction at constant performance compared to planar or "2D" transistors. The original transistor developed by Bell Labs in 1947 was meant as a replacement for the vacuum tube and was large enough to be assembled by hand. Intel's 22nm tri-gate transistors however are so small that you can fit more than 4000 of them across the width of a human hair approximately 90 microns in diameter. The total transistor count is at 1.4 Billion on a 160mm^2 die size, up from Sandy Bridge's 1.16 Billion.
Ivy Bridge is a "tick" to Intel's Tick-Tock release model followed since 2007. This means it is a derivative architecture from Sandy Bridge on a new process node, although with enough "tock"-like changes to the graphical sub-architecture. On the new 22nm processor node, the top TDP dropped from 95W to 77W, a significant leap considering the performance improvements as well. This may not be as important for desktop users, but for mobile and notebook users, this translates to longer battery life and better thermal performance. Ivy Bridge also introduces a new high performance digital random number generator as well as a new RdRand instruction which can be useful for encryption algorithm and security purposes. Intel also introduces a Supervisory Mode Execution Protection (SMEP) feature which provides hardware protection against malicious user code executions and prevent escalation of privilege (EoP) security attacks. The Ivy Bridge architecture otherwise looks relatively similar to Sandy Bridge with the use of a ring bus architecture across all cores, system agent, graphics and the shared L3.
Both 3rd generation Core processors and the new 7-series Panther Point chipset are cross compatible with 2nd generation Core processors and 6-series Cougar point chipsets, allowing for a flexible upgrade transition and maximum compatibility. This means you can use 3rd generation Core processors with all LGA1155 socket motherboards and use 2nd generation Core processors with the latest Panther Point chipset motherboards. Understandably, some new features inherent in the latest generation products will only be available with a latest generation processor or chipset and BIOS updates are required for full compatibility. Unlike Sandy Bridge, all 7-series chipsets will have processor graphics support and Intel SRT SSD Caching feature (except for the Z75 platform) so there will not be a P77 chipset motherboard to replace the P67 chipset. USB 3.0 is also now natively supported on the 7-series chipset family, with up to four ports delivering 10x USB 2.0 transfer rates. This eliminates the need for 3rd party USB 3.0 controllers and provides fast USB 3.0 external drive booting options.
The display engine is integrated into the Ivy Bridge processor and has full DirectX11, OpenGL 3.1 and OpenCL 1.1 functionality, making Ivy Bridge a viable gaming platform with over 100 games playable out of the box. The HD Graphics 4000 has up to twice the compute throughput, 16 Execution Units (up from 12) and can drive three simultaneous non-symmetric independent displays. The HD graphics subsystem infrastructure has been redesigned to handle heavier loads more efficiently with the L3 cache The new graphics architecture adds two programmable stages as well as a dedicated fixed function Tessellator. It also boasts new compressed texture format support (BC6H/7), Compute Shader Support, improved geometry performance, increased peak GFLOPs, increased Hi-Z performance and improved sampling throughput. As for discrete GPU support, similar to Sandy Bridge, there are 16 PCI-E lanes from the CPU but when paired with a 7-series chipset, they are fully PCI-E 3.0 capable.
Similar to Sandy Bridge processors, unlocked "K" processors will have a fully unlocked core and present flexible overclocking options compared to the regular non-unlocked Ivy Bridge processors. The Z77 and Z75 chipsets provide CPU performance tuning options while all 7-series motherboards will have processor graphics overclocking capability. Ivy Bridge supports 2 channels of DDR3-1600 memory, up to 2800 MT/s in 200 MT/s increments compared to 2133 in Sandy Bridge and is XMP 1.3 capable. Core ratio overrides can be adjusted in 100 MHz increments and has a maximum of 63 compared to 57 in Sandy Bridge. Meanwhile Processor graphics ratio overrides can be adjusted in 50 MHz steps and has a ceiling of 60, up from 57 in Sandy Bridge. Ivy Bridge is also introducing Real-time core ratio change for both the CPU and GPU core.