Haswell for Desktops in Detail
What is introduced under the name of Haswell is the latest upgrade of the Core microarchitecture. It is going to be used for all modern desktop platforms manufactured in the next couple of years, except for the LGA2011 infrastructure designed for Sandy Bridge CPUs. The Haswell doesn’t have much to offer when it comes to desktop PCs, actually. Such CPUs will be still manufactured on 22nm facilities using 3D transistors. As for new features, they support FMA3/AVX2 instructions, have faster L1 and L2 cache, and offer certain optimizations in terms of parallel execution.
The lack of fundamental improvements can be easily noticed in the Haswell semiconductor die which not only looks like an Ivy Bridge die but is also similar in size and configuration.
The quad-core die of a desktop Haswell (one that features the GT2 integrated graphics core) incorporates 1.4 billion transistors and measures 177 sq. mm. Its Ivy Bridge counterpart was only 15% simpler, incorporating 1.2 billion transistors (we mean the overall design complexity that doesn’t account for duplication of certain elements in the die). Half the added transistor budget is responsible for the graphics core which now amounts to 30% of the whole CPU die, so there is little left for any changes in the microarchitecture of the x86 cores.
As a result, there are no dramatic changes in the specifications of the new CPUs. The CPU families still have the same number of x86 cores and the same technologies. The clock rates and cache memory amounts haven’t changed much, either. You can see this in the CPU specs Intel is going to announce in three days.
So the senior desktop Haswell CPUs have almost the same specifications as the flagship products of the previous generation. That’s why we can’t expect any performance benefits thanks to higher clock rates or larger cache. There are only two points of difference. First, the desktop Haswell’s graphics core is obviously faster than the Ivy Bridge’s just because there are more execution devices in it. And second, the TDP is increased from 77 to 84 watts because some voltage regulator components have been moved into the CPU die.
The Core i7 series differs from the Core i5 in the same way as before. Both series include quad-core CPUs but the Core i7 supports Hyper-Threading. And the topmost model in each series is still an overclockable K-indexed CPU with unlocked multiplier. However, Intel doesn’t offer different graphics cores in its new quad-core CPUs now, therefore all of them use the mainstream GT2 core with 20 execution devices. The junior graphics core GT1 is likely to be limited to junior CPU series.
The price policy doesn’t seem to be any different, either. The price gap between similar CPUs of different generations will be no larger than $10.
We should also add that we’re not describing the entire desktop Haswell model lineup here. Intel is actually preparing an unusually massive release to introduce, besides Core i7 and Core i5 CPUs for ordinary PCs, specialized CPU versions with S index (with a TDP of 65 watts), T index (with a TDP of 45 or 35 watts) and R index (in BGA packaging with GT3 Iris graphics core). We’ll discuss them separately in our upcoming reviews.