so the other day i was shopping for a state-of-the-art CPU for my gaming and
productivity pc when i realized that Intel's latest 5820k and 5930k
both have six processing cores with hyper threading both have 15 megs of
cash they have a clock speed difference of only six percent and yet the
difference in retail price is around 200
oh there's the gotcha the 5820k only has 28
pci express gen 3 lanes you know the electrical connections behind the slots
that we use for graphics cards and other expansion cards compared to 40 on the
5930k what a strange way for Intel to
differentiate its mid-tier 2011 3 CPU from its entry-level one
Corsair gaming RGB keyboards feature precision cherry mx RGB key switches for
16.8 million color per key backlighting for virtually unlimited customization
click now to learn more let's start with a brief explanation of what pci express
or PCIe lanes are and what they're good
for unlike previous expansion slots like agp and pci pci express has a physical
size and an electrical operating mode
that can be independent from each other power is provided by the pins near the
key in the connector and the rest of the connector is used or not used to provide
more or less bandwidth to the device that is plugged into it the more
bandwidth the more lanes are said to be being used for communication the most
common speeds are 1x 4x 8x and 16x so
here's a cool fact the different bus width cards and slots are actually
interoperable that means that installing a 1x card in a 16x slot is fine and you
can even go the other way around in this video i cut out the back of a smaller
slot and put a larger card into it all
that happens is that both the slot and the card will now operate at the speed
of the lowest link in the chain so that's what's going to happen if we
plug our PCIe 16x graphics card into
what appears to be a 16x slot but if the
CPU in our system doesn't have enough pci express lanes to provide the full 16
lanes your motherboard manual will give you more specifics with a slot by slot
breakdown of how it's going to work but basically it'll simply interface with
your pc at a lower speed usually 8x
well that sounds horrible Linus won't cutting the link speed to my graphics
card in half tank its performance not necessarily we're on the third
generation of pci express with each new generation doubling the theoretical
speed of the previous one that means a modern gen 3 PCIe 16x slot can
communicate four times faster than an original gen 1 16x slot or another way
of thinking about this is that a gen 3 4x slot is equivalent to a gen 2 8x or a
gen 1 16x slot but while we already know that from
countless articles that exist on the topic in the past that no previous
generation of 8x slot has bottlenecked a then modern high-end graphics card with
x99's positioning as the high-performance platform of choice for
enthusiasts and for gamers i think it's fair to say that folks may be running
not just one but two or even more
graphics cards at a time and this is where concerns start to arise especially
given that AMD and i suspect also NVIDIA is starting to do more inter-card
communication over pci express when running in crossfire and again i suspect
sli versus relying on those dedicated connectors on the top of the cards
so let's introduce the test to eliminate the variable of the slightly different
clock speed of the two cpus and since overclocking k-series chips is so easy
these days we're gonna run both processors at four gigahertz a very
conservative overclock that anyone should be able to attain for the rest of
the bench we've got a Gigabyte x99 gaming five four-way sli compatible
motherboard with 16 gigs of ddr4 2400 megahertz memory from adata thanks to
both of them for providing the hardware for the test bench we're going to be using four NVIDIA GeForce gtx 980 4gb
graphics cards and we're going to be running all this off of course our ax
1500i power supply so that nothing melts during the benchmarking process and here
are the numbers fraps was used to take average frame rates for each of our
standard test runs and all games were run at 4k on pretty demanding settings
to ensure that we were pushing the hardware as hard as possible as expected
a single graphics card config is not affected in any way since it's running
in 16x mode on either CPU but dual cards
will be running at 8x8x on a 5820k and
16x16x so an effective doubling on a 5930k so i guess as much as it might be
a little bit more counterintuitive they both ran the same so there you go
in three-way sli both cpus have to give up at least one 16x slot but again the
results are not really affected in any way beyond sort of your standard
variance from one run to another and then finally in four-way sli we see oh
actually there's a difference here as you may or may not have noticed our 28
lien CPU doesn't have any numbers for 4-way sli NVIDIA requires graphics cards
to be plugged into an 8x slot at least for sli certification so only 40 lane
cpus have support for this configuration however it should be noted that even at
4k the benefit of a fourth card is fairly small and three-way remains our
recommended max config even if you feel the need to spend over a thousand
dollars on a bunch of graphics cards to put in your system it should be noted
that AMD does not have the same limitation for crossfire so you could
run four graphics cards if you really wanted to in that case but our
recommendation remains the same anyhow
so that's the story or at least most of it for gamers anyway compared to the
mainstream z97 platform where it should be noted that even the highest end cpus
have a mere 16 lanes Intel's enthusiast x99 platform in general and the core i7
5820k CPU in particular is a great
choice even for multi graphics card gamers if they want to reap the benefits
of an extra two processing course ddr4 memory and higher overall memory
capacity limits things do get a little bit dicey for
non-gamers though when it comes to other pci expansions so make sure that you
consult the manual of the motherboard you want before investing in this
particular CPU because you may find that the m.2 high speed storage slots
and in some cases even built on ports like SATA express and usb 3 headers
might not work with too many pci express
cards plugged in or even be available at all with a 28 lane CPU so if in doubt
head over to the cpus and motherboard section of the Linus techtips.com forum
where our helpful community will get you sorted out
thanks for watching guys i hope this video put to rest some of the concerns
about oh no the affordable one doesn't have enough pci express lanes i hope you
all feel a little bit better like the video if you liked it dislike it if you
disliked it leave a comment letting me know did you learn something today is
this something you already knew was it nice to have it validated anyway also
check out the link in the video description you can support us by buying a cool t-shirt like this one giving us a
monthly contribution or that other thing right changing your amazon bookmarks one
with our affiliate code so we get a small kickback whenever you buy cpus or
graphics cards or whatever else thanks again for watching and as always don't
forget to subscribe
you