Whether you’re building your
next PC or shopping for a new computer online, one of the questions that
comes up from time to time is whether the Intel Core i5 or Core i7 is a
better bargain. The short answer, “It depends,” isn’t all that helpful,
so we’ve broken the data out in more detail and for both mobile and
desktop processors. Here’s what you need to know.
Mobile Core i5 vs. Mobile Core i7
Because
Intel has launched a reasonable set of SKUs for its 5th generation
(Broadwell) hardware, we’ll use those chips for comparing the Core i7
vs. Core i5 stack. All of Intel’s mobile Core i5 processors are
dual-core chips with Hyper-Threading, going right back to Sandy Bridge.
What distinguishes modern 5th generation Core i5s is their TDPs — Intel
offers Broadwell in 15W, 28W, and a single 47W SKU. That chip, the Core
i5-5350H is also capable of addressing 32GB of RAM and offers Intel’s
Iris Pro 6200 solution based on Crystal Well.
Intel’s Core i5 mobile lineup (Broadwell)
Here are the features that separate mobile Core i5 and Core i7 processors:
More cores:
Many of Intel’s Core i7 processors are quad-core chips with
Hyper-Threading enabled. This isn’t universal, however, and the company
does offer five dual-core + Hyper-Threading SKUs.
Higher clocks:
Intel’s dual-core mobile Core i7 chips typically have higher clock
speeds than their Core i5 counterparts, even at the same TDP. The
fastest dual-core Core i7 at 15W TDP is the Core i7-5600U, which runs at
2.6GHz base and 3.2GHz standard. The fastest Core i5 at 15W is the Core
i5-5300U, which has a base clock of 2.3GHz and a max clock of 2.9GHz.
The GPU on the Core i7-5600U is clocked 50MHz faster as well.
More cache: Core i7 chips carry either 6MB or 4MB of cache. Core i5 chips have 3MB, except for the Core i5-5350H, which has 4MB.
More addressable memory:
Most of the Core i7 chips are limited to 16GB, like the Core i5, but
there are four exceptions. The Core i7-5850HQ, 5950HQ, 5750HQ, and
5700HQ are all capable of addressing up to 32GB of RAM.
One important thing to note,
however, is that how much performance you get out of a Core i5 vs. a
Core i7 will depend a great deal on your laptop’s cooling solution and
whether or not the chip can handle its own heat output. We’ve previously
discussed how Intel gave OEMs more freedom to define their own TDP
targets and skin temperatures, but this creates scenarios in which buying a faster Core M can actually result in worse performance as the chip hits its thermal trip point and down-throttles to keep cool.
Intel’s highest-end Iris Pro graphics are available in both Core i5 and Core i7 mobile SKUs
We
can’t point to specific instances where this has tilted performance
between Core i5 and Core i7 chips, but it’s likely to create at least a
little “slosh” between the two core families. Generally speaking, if you
truly want to emphasize low power, pick the CPU that has lower base and
turbo clocks. Intel historically defined TDP as “The CPU’s average
power consumption when running typical workloads over a period of time.”
A chip with more headroom is a chip that’ll hit its throttle point
faster.
Desktop Core i5 vs. Desktop Core i7
Because Intel has only launched a
handful
of Core i5 and i7 desktop parts, for now we’ll focus on the 4th
generation cores (Haswell). One significant difference between the
desktop and mobile markets is that all but one of Intel’s 23 Core i5
SKUs offer four cores, but no HyperThreading. Intel’s Core i5-4570T is
the single exception to this — it’s a dual-core + HyperThreading chip.
Another difference between the mobile lineup vs. the desktop cores is
that the desktop versions of both the Core i5 and Core i7 officially top
out at 32GB of addressable memory.
In fact, many of the
differences we observed between mobile parts don’t apply to desktop
hardware. The i7 family still carries more L3 cache (8MB, save for the
Core i7-4770R, which has 6MB), as compared to the Core i5 family, which
has 6MB of cache on every chip except for the Core i5-4570R, 4570 and
4670R, which have just 4MB. Clock speeds are a mixed bag — while the
fastest Haswell Intel manufacturers is the Core i7-4790K at 4GHz base
clock and 4.4GHz Turbo, the Core i5-4690K is clocked at 3.5GHz base and
3.9GHz Turbo — essentially equal to the Core i7-4770K.
Both the
Core i3 and Core i5 families use Intel HD Graphics 4600 solution with
the same 350MHz base clock and 1.2GHz maximum clock. Apart from
Hyper-Threading and some small cache differences, the Core i5 and Core
i7 are quite similar, with overlapping frequency ranges and feature
sets. Support for Intel’s TSX-NI instructions is only available on one
Core i5 SKU, but only two Core i7’s offer the capability.
Similarly,
Intel only offers vPro on 13 of the 23 Core i5 SKUs, compared to 9 of
the 12 Core i7 SKUs — but if you want vPro on a Core i5, you can get it.
