Which CPU is better in a laptop?
The 6700HQ or newer 8550U from Intel?
We’ll find out in this video with a series of benchmarks to see how they perform, and
discuss the differences between them to help you decide which you should get, or if it’s
worth upgrading.
I recently compared the 8550U against the 7700HQ in another video, and had a few comments
asking to also compare it with the even older 6700HQ, so here we go!
Late last year Intel launched their 8th generation of mobile processors known as Kaby Lake R,
which were a refresh of the 7th generation known as Kaby Lake, rather than being Coffee
Lake based.
The mobile Coffee Lake chips are on the way, but for now we’ve only got the U series
and desktop processors, and 6700HQ CPU is from the 6th generation known as Skylake.
First let’s note the similarities between these two mobile chips.
Both have 4 CPU cores with 8 threads, which is the main reason that I wanted to compare
them, and both are based on a 14nm manufacturing process.
That’s where the majority of important similarities ends, so how do they differ?
The main difference is that the clock speed of the newer 8550U varies quite a bit, with
a base frequency as low as 1.8GHz and a turbo boost up to 4GHz, while the older 6700HQ has
a 2.6GHz base and 3.5GHz turbo speed.
This is because the 8550U is a lower powered chip with a 15W TDP compared to the 6700HQ’s
45 watts, and its performance greatly depends on how much power is being applied as well
as the cooling solution.
The Dell XPS 13 which I’m testing with here is configured to use up to 25 watts though,
so in general it does perform better than many other 8550U systems.
The 6700HQ also has 6MB of cache, while the 8550U has a bit more at 8MB.
So there are some interesting differences between the two, mainly with the clock speeds
and of course the power difference.
How much of a performance difference does this make practically?
To test this I’ve run some CPU specific benchmarks on two different laptops with these
processors to find out.
Both laptops are running Windows 10 with all available updates installed on an SSD.
The 6700HQ laptop has 16GB of DDR4 memory running at 2,133MHz, while the 8550U laptop
only has 8GB of LPDDR3 at 1,866MHz, so a small amount of the performance difference may be
due to this and is worth keeping in mind.
Overall the laptops aren’t too different in terms of specs, we should still be able
to compare the CPUs for the most part.
In Adobe Premiere I’ve rendered my review video on the ASUS Zephyrus gaming laptop,
which goes for around 10 minutes at 1080p, using the h264 high bitrate preset.
No GPUs were in use for the test, these results are CPU tests only.
We can see that there’s a fair difference between the two, with the 6700HQ able to better
handle sustained multicore speeds.
Next i’ve used Handbrake to encode a 4K video file to 1080p, and a separate 1080p
video file to 720p, and in both cases the 6700HQ has taken the lead by over 10%.
I’ve used Veracrypt to test the AES encryption and decryption speeds, and in my testing the
8550U performed a fair bit better than the 6700HQ in both.
The 7-Zip benchmark was used to demonstrate the decompression and compression speeds of
both CPUs, and interestingly although the 8550U was quite far ahead in terms of compression
speeds, but it was a little slower when it came to decompression.
In Cinebench I’ve tested both single and multi core performance, and as expected in
the single core the 8550U is out in front as the single core was able to reach 4GHz.
Things change in the multicore results however, as the 8550U had to downclock itself quite
a bit to stay cool, resulting in the 6700HQ performing better.
Interestingly things change a bit in Geekbench4, although the single core performance is slightly
ahead as expected, the multicore performance result here jumps ahead too, however this
test doesn’t go for that long and doesn’t really represent a sustained workload as some
of the other tests better do.
A similar result was observed in Passmark 9, where the single core score of the 8550U
was a fair bit ahead, while in the multicore test the results were much closer together.
The Corona benchmark renders a scene using the CPU, and it completed about 10% quicker
on the 6700HQ, again because the 8550U was downclocking itself under a full multicore
workload over a longer period of time.
So as with the 7700HQ comparison, the results were a bit of a mixed bag, with the 8550U
winning in single core performance as expected, and in general losing in multicore performance,
at least in the tests that I’d classify as being more real world with workloads that
run for a longer period of time rather than short synthetic tests.
The single core wins by the 8550U were expected, owing to that 4GHz turbo boost, which is higher
than the 6700HQ’s 3.5GHz, and it’s also just a newer chip with other architectural
improvements.
In practice I found that the 8550U with all cores in use quickly thermal throttled to
around 2.7GHz on all cores, at least in this case with the Dell XPS 13 that I was testing
with, which is quite thin and doesn’t seem to be up to the job of running it flat out
for longer periods of time.
The Dell XPS 13 does use a 25W TDP, so the CPU is getting more power, helping it perform
better compared to other ultrabooks with the standard 15W TDP.
The thin form factor does seem to limit the results though.
With proper cooling the 8550U is meant to run at 3.7GHz on all 4 cores, making it a
fair bit better than the 6700HQ’s all core 3.1GHz boost.
As a lower power chip it’s been placed into a small laptop here, so there’s not enough
thermal headroom to achieve maximum performance.
There were no issues running a single core at 4GHz with the 8550U though, which explains
why it’s ahead in many of the single core tests, but generally behind in the multicore.
With better cooling I suspect that the 8550U would come out on top in almost all cases,
due to that higher clock speed, however as a U series chip which is primarily going to
be used in much thinner laptops this may be unlikely.
Based on these tests in most cases the 8550U seems to offer some improvement, mainly in
single core workloads.
If you’re already running a laptop with a 6700HQ there’s no real reason to upgrade
to the 8550U, unless perhaps you need to buy a new laptop anyway for other reasons, such
as a requirement for a thinner machine, or maybe you just really want that better single
core performance.
I still use my 6700HQ laptop every day and it still performs perfectly fine for me, so
I’d probably only consider the change if I wanted to swap to a ultrabook style system.
I haven’t tested the differences in battery performance or temperatures, as both laptops
have different sized batteries and different cooling solutions it wouldn’t be a fair
comparison.
For the same reason I also haven’t tested any games, as the 6700HQ laptop had an Nvidia
card while the 8550U laptop had no discrete graphics at all.
So what did you guys think about the differences in performance between Intel’s 6700HQ and
8550U CPUs?
Although the main point of the U series CPUs are to be low powered and allow for thinner
and lighter laptops, the fact that the 8550U was able to keep up and in many cases even
beat the 6700HQ in some instances was pretty impressive.
I’d be interested in seeing what the 8550U can do in a thicker laptop with better cooling,
and I can’t wait to test out more 8th gen CPUs on the channel in the future.
Be sure to let me know your thoughts down in the comments, and leave a like if you found
it useful.
Thanks for watching, and don’t forget to subscribe for future videos like this one.