Intel Core: The Greatest Generation

The CPU previously known as "Sandy Bridge" has been officially released as the Second Generation Intel Core Processor. This latest Core revision is built on a 32-nanometer process and includes almost a billion transistors. This is an evolutionary step up the CPU ladder, and simply builds on what the original Core processor brought to the table.

But that should not discount its importance, as Intel has incorporated many new enhancements into the Second Generation Core, such as an innovative ring interconnection that serves as the communication hub for the entire CPU. This is also the first Intel processor to include an on-die graphics component directly on the silicon.

These two factors are integral to Intel's continued success in the processor market, and not only against perennial challenger AMD, but also the upstart ARM. Therefore, while the Second Generation Core is not a brand new microarchitecture, it is still a very important release for Intel.

Crossing the Sandy Bridge

Intel has released several Second Generation Core models in the i3, i5 and i7 dual- and quad-core families. These include the entry-level Core i3 with 3MB of Level 2 cache and speeds up to 3.3GHz; the mainstream Core i5 sporting 6MB of cache and the same 3.3GHz clock; and the high-end Core i7 with a full 8MB of cache and a 3.4GHz top speed.

The mobile versions of the Second Generation Core architecture differ from their desktop counterparts in terms of clock speed and thermal design power (TDP), as well as retail price. The mobile parts top out at a clock speed of 2.6GHz, but feature a TDP as low as 17 watts. At the top end of the mobile scale, the power draw is a bit higher, as the 2.5GHz Core i7-2920XM Extreme Edition tops out at 55W, or higher than the 35 to 45 watts of the low-power "T" models in the desktop line.

Intel also offers (at a slight premium) two unlocked models, the 3.3GHz Core i5-2500K and 3.4GHz Core i7-2600K. The "K" suffix means that the processor is fully unlocked, and the price premium over a standard model is quite nominal (in the $10 to $30 range) and worth it even for corporate buyers seeking higher returns.

HyperThreading is only included on a few of the mainstream Core i5 models, while being a default feature of the Core i7 and i3. Turbo Boost has been upgraded to version 2.0, and is supported in the Second Generation Core i7 and i5 lines, but not at the Core i3 level.

Virtualization is another factor in any buying decision, and Intel has decided to limit Intel Virtualization to the Core i7 and i5 lines, while leaving specific VT support out of the unlocked "K" models. It is the same story with Trusted Execution Technology (Intel TXT), which is again not present on the "K" processors.

Intel will also be offering a variety of new desktop and mobile chipsets for the Second Generation Core CPU line. On the desktop side, the company will take a very familiar dual-tiered approach with an H-series and a P-series. The P-series is designed for the performance sector and does not support integrated graphics, while the H-series is more entry-level and allows the use of Intel's onboard graphics.

At presstime, the chipsets made a splash -- and interrupted the Sandy Bridge system rollout -- when Intel discovered a bug that slows Serial ATA data transfers over time in all chipsets based on its "Cougar Point" circuitry. The flaw is in the chipset, not the processor, and Intel says it has already been fixed, but widespread availability of Second Generation systems has been pushed back to April.

Onboard Graphics Make the Grade

The Second Generation Core processors all include some form of integrated graphics core, or in this case, Intel HD Graphics 2000 or 3000. The latter features 12 execution units, while the HD 2000 has only six.

The Intel HD 3000 is a very scarce part, only finding its way into the two Core i5 and i7 "K" models, while the rest of the line receives the lower-end HD 2000. Default GPU clock speeds remain consistent at 850MHz for all models, but these can be increased with Intel Graphics Turbo dynamic acceleration. The majority of Second Generation Core models jump to 1100MHz, but only the top-end Core i7 2600-level processors can go as high as 1350MHz.

Overall performance has certainly improved over previous Intel HD graphics, but we are still not at a point where discrete video cards can be tossed in the garbage can. Mainstream 3D games and applications run just fine, assuming you keep detail settings at realistic levels, and the Intel HD 3000 does hold its own against entry-level cards from AMD and Nvidia.

But once you move beyond that level, even the mainstream discrete GPUs leave Intel in the dust. Integrated graphics have to move above the entry level in order to attract desktop buyers, and Intel will need to add more execution units before it hits that point. Then again, the Second Generation Core has immediately made several low-end GPUs obsolete.

Video playback and encoding performance is a very important part of any PC nowadays, and Quick Sync technology supplies the fixed-function hardware acceleration on the Intel HD GPU. Quick Sync can handle multiple HD video streams and Intel states that it allows HD video to be converted twice as fast as a first-generation Core processor. By offloading this function from the CPU, it can also increase overall system performance.

The only hitch is that you need to be using the Intel HD onboard graphics on an H-series motherboard to make use of this feature. If you are running a dedicated graphics card, you cannot make use of Quick Sync, even if you have a supported Second Generation Core processor.

Changing the Tweaking Rules

Intel has long been a proponent of CPU overclocking, promoting its products as having more headroom than AMD, and even producing hardcore motherboards with extensive tweaking features. The CPU headroom still remains, but because the clock generator of Sandy Bridge resides on the CPU, and the ring bus incorporates multiple system bus speeds into one, simply increasing the bus speed on the motherboard is no longer a viable option.

This effective limit on overclocking has a definite impact in terms of microarchitecture comparisons, as the performance race changes considerably when performance tweaking is taken into consideration. While the new Core processors are faster than their first-generation counterparts at default speeds, even a first-gen Core i5 or i7 "Lynnfield" overclocked to its top speed is faster than a corresponding Second Generation Core with a locked core speed.

Intel's solution to this effective limit on Sandy Bridge overclocking is to offer enthusiasts an unlocked "K" model. Both the Core i5-2500K and i7-2600K have fully unlocked clock generators that can be increased well past their default settings. Early efforts have produced exceptional results, and ramped-up speeds of between 4GHz and 5GHz point to exceptional headroom on these latest processors.

The overall design of the Second Generation Intel Core is that of a mobile processor, with the desktop variant being more of an afterthought. Because of this, Intel may actually lose market share at the desktop level, as limitations may force performance-minded customers to go with a more tweak-friendly Phenom II. But none of these issues exists at the mobile level, as most laptop owners will never worry about a lack of overclocking or complain about paying for integrated graphics.