Although we’ve taken our first look at several Haswell-based Core i5 processors in this review, we don’t have much new data. These CPUs just have the same highs and lows as the Haswell-based Core i7 series we tested earlier.
To be specific, the new Core i5 4000 series are an average 5 to 10% faster than their 3000 series predecessors thanks to improvements in the Haswell microarchitecture. Their clock rates haven’t changed. We could also see that the new CPUs have high potential in the way of the new AVX 2.0 instruction set. AVX 2.0 is hardly used by existing software, but its universal adoption may make the Haswell much more attractive in the future.
That said, it is questionable whether the Core i5 4000 series are superior to their predecessor on all points. There are important consumer properties other than sheer performance, and the Haswell microarchitecture has certain problems in this respect.
The flagship model Core i5-4670K is indeed faster than any other Core i5 and can even challenge the heavyweight Core i7-3770K at single-threaded loads but its overclocking potential is lower even if compared with the Core i5-3570K. We could only overclock our Haswell to 4.5 GHz whereas same-class CPUs with Ivy Bridge design could be overclocked by 100-200 MHz more. Of course, the overclocked Core i5-4670K is still going to be a little faster thanks to its more progressive microarchitecture, but Haswell CPUs call for a new platform. You have to buy a new mainboard to use them. That's why upgrading to the Core i5-4670K from an earlier Core i5 doesn’t make sense. You may only want to choose it if you're building a completely new computer.
The midrange Haswell variants, Core i5-4670 and Core i5-4570, offer rather high performance as well, being occasionally faster than the Core i5-3570K. The problem is that Intel has prohibited overclocking them (and the rest of non-K Haswell-based CPUs) in the limited way which was possible before. It means the midrange Core i5 Ivy Bridge CPUs can easily be overclocked to 4.0 GHz whereas the new Core i5 series don't offer such an opportunity.
The junior Haswell-based CPU available at the moment, Core i5-4430, looks very odd. It is comparable to the Core i5-3470 in price but nearly always inferior to it in performance. It can hardly be recommended even for completely new configurations. The time-tested LGA1155 platform would be a better choice.
Thus, the new Core i5 4000 series CPUs may only be really interesting in just a few scenarios. You may want to choose the Core i5-4670K if you want to build a new computer and overclock your CPU. Or you may want to choose the Core i5-4570 if you are not going to overclock your new computer and your CPU budget is limited to $200. Otherwise, preferring the Haswell and switching to the LGA1150 platform is hardly rational.
There is one important exception, though. We shouldn’t forget that the new microarchitecture features an improved integrated graphics core whose performance has grown much more than the x86 performance. We didn't cover this issue in this review since we had tested the HD Graphics 4600 earlier. But if you need a hybrid processor with a fast x86 part and a functional graphics core, the Haswell is quite a good option.