WEBVTT

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this heatsink right here pointless

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four RAM slots you only need two of them and why is

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there a pci express slot that has sli no

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one uses it why the heck does everybody want all of this

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it's because nobody actually knows what motherboards are and how they work so

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here it is to the best of our ability how motherboards work so

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buckle up nerds land is on vacation and we're not holding back just like i can't

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hold back this segway to our sponsor i fix it you'd like to repair your own

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electronics instead of having to spend hundreds on expensive replacement or

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repair services learn more about ifix's essential electronics toolkit at the end

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of this video

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computer power supplies output 12 volts

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if you apply 12 volts to a CPU it'll look something like this

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hmm sub-optimal for sure

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sub-optimal for sure to avoid the magic smoke we need to take

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that 12 volts and step it down to something more like 1.2 volts and this

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is exactly the job of voltage regulation modules the vrms that overclockers talk

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about so much the basic circuit consists of two

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mosfets which in this situation are basically just fancy switches

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an inductor and a diode this first switch closes

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which then charges this inductor converting the electricity into a

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magnetic field the voltage the CPU gets

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depends on how long this switch is closed but the instant it is opened the

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voltage to the CPU begins to drop kind of like a

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drain so this is where that diode here is very

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important if both switches are open while the inductor is charged its

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magnetic field will collapse and pop goes your CPU

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but the diode is highly inefficient so it's important to get the second switch

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closed as soon as possible to avoid creating any unnecessary heat if you're

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paying attention you might have noticed a problem here though although the

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voltage will be bouncing around what the CPU is asking for there are a lot of

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spikes not great for stability and there are two ways to remove this the first is

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to just increase how fast the mosfet switches on motherboards this is

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normally done at about 300 000 times per second but even then the voltage can

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fluctuate more than the CPU wants and it isn't practical to try switching a whole

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lot faster than that every single time the mosfet switches on or off it

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generates a bit of heat and above about 150 degrees celsius the mosfet's gonna

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die so if we want cleaner power we don't

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need faster mosfets we need more of them

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the circuit we have here represents a single phase another term that

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overclockers love to use so much so by adding another phase we can

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roughly double how clean our power is with the benefits of additional phases

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scaling roughly linearly from there the number of phases in your motherboard

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is normally shown as a number like eight plus two which means eight phases for

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the CPU and two dedicated for the RAM let me put this away

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multiple phases also have another benefit say your CPU requires 100 amps

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to run with a single phase all 100 amps would have to go directly through those

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components but with two phases only 50 amps will go through each phase meaning

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lower rated and thus cheaper components can be used

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you might be tempted to think then well more phases equals more better

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which is true to a point however as you add more phases controlling them can get

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more difficult which translates into the vr as being less able to respond to

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changes in voltage like everything then there are trade-offs between having less phases

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with higher quality components or more phases with lower quality components

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this does create a rather odd situation though

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high-end motherboards normally have the most phases

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and the highest efficiency components

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which means the vrm temperatures should be really low

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but these motherboards also have the best vrm heatsinks

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why purely to look cool mid-range boards

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might actually need good vrm cooling but for anything other than extreme

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overclocking a high-end board would probably be fine with no vrm heatsinks

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at all it's similar to how you'd be fine without a shirt from ltdstore.com but

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definitely look cooler with one now that the CPU has power how does it

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talk to the rest of the system this copper wire represents how far an

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electric signal can travel in a nanosecond

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oh everything falls at 5000 megahertz your RAM can send data every 0.2

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nanoseconds in that amount of time an electric signal can travel

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this far so then this

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is physically impossible RAM makers have lied to you although on

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your RAM stick in the BIOS and in Windows your RAM will say it's running

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at 5000 megahertz or whatever in reality it's completing 5

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mega transfers per second what's the difference well since it's ddr or double

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data rate RAM transfers are done on both the beginning and the end of each

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individual hertz this means the sticks are actually running at 2 500 megahertz

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which is why if you've ever looked in CPU-z the RAM shows up as half of what

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everything else claims it is depending on what you want to do with your

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motherboard knowing how the CPU and the RAM connect can be important like have

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you ever wondered why the manual always says to put the RAM in the second and

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the fourth slots on your motherboard for this example we'll be looking at a CPU

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with dual RAM channels this is the most common configuration

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for consumer cpus but the same basic principles apply to workstations or

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server processors with more channels the absolute best case scenario for a dual

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channel CPU is to simply have two RAM slots

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pcb traces go directly from the controller to the RAM stick with nothing

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else in the way this is why ASUS's top tier gaming boards only have dual slots

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and also why some itx motherboards like this one can punch way above their

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weight class when overclocking RAM moving on to motherboards with four RAM

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slots here you have two main options t

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topology and daisy chaining t topology is when the traces to each

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RAM stick on a channel are the same length which can be great for running

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all four slots at relatively high speeds but if pure speed is what you're after

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then daisy chaining is the way to go with a daisy chain motherboard the

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traces basically just go to one slot and then continue on to the next one this

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can cause the speeds to be lower when all four slots are used

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the timing differences between the two sticks has to be figured out by the controller but it also means with only

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two sticks you can run them at nearly the same speed as if there are only two

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slots now it is important to use the correct slots though if an electric

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signal goes through a wire and the wire suddenly ends with nothing connected to

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it like this the signal can reflect back creating

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noise in the circuit by putting the RAM sticks in slots 2 and

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4 the traces end at the RAM stick reducing noise in the circuit and

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allowing for higher speeds so basically before you buy RAM check if your

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motherboard has daisy chain or t topology since it determines if you

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should get two higher capacity sticks or four lower capacity ones with higher

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capacity dims getting cheaper and cheaper it now would make sense for most gaming

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motherboards to only have two RAM slots optimized to go as fast as possible our

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contact at ASUS agreed but said way too many people will complain that they

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can't upgrade their memory in the future even if statistically very few people

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actually will do that but even without topologies and slots like if you had the

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CPU right next to the RAM and used gold traces or whatever for the perfect

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signal there would still be something else holding you back

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the memory controller on the CPU everyone has accepted at this point

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there's a silicon lottery and some cpus will naturally be able to clock higher

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at lower voltages but the same applies to the memory controller on the CPU your

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luck in the silicon lottery can sometimes have the biggest effect on how

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fast your RAM runs the CPU and RAM are now working but we

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still need to be able to connect things like a GPU storage and peripherals in

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the past this would be done through the chipset with the northbridge taking care

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of PCIe and memory will the southbridge handle i o storage audio usb

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you know on modern motherboards though the memory

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and some PCIe lanes are connected directly to the CPU while a chipset

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handles everything else which simplifies the layout and allows for lower

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latencies losing a whole chip is big but what's even more shocking is just how

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fast PCIe has become with PCIe 4.0 a one

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lane slot can do up to two gigabytes per second and a 16 lane slot is able to

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transfer a staggering 32 gigabytes per

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second that's close to the speeds of ddr4 RAM how how the heck can they pull

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this off simple very expensive pcbs previously it

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was possible for lower end motherboards to have only like four or so layers but

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now in order to get PCIe 4.0 levels of signal quality 8 to 12 layer pcbs are

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basically a requirement given every two layers can come with a 20 to 30 cost

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increase for the pcb the insane prices of modern motherboards start to make a

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bit more sense even if the majority of users will struggle to saturate a PCIe

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3.0 connection let alone 4.0 so you might have noticed

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a bit of a theme here one of the most difficult parts of designing a

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motherboard isn't creating the best possible product but carefully balancing

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the actual value and perceived value

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like this motherboard right here supports sli has massive vrm heatsinks

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it has four dimms because those are things that people expect it'd probably

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be better for the majority of users if there were just two RAM slots closer to

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the CPU one PCIe connector and you know

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the price of this one down here was turned into better traces and

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okay the vrm heatsink it looks pretty cool and

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i wouldn't want to give it up but at least i know that that's a trade-off

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that i'm making and hopefully in the future we can be more open to crazy

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motherboard designs that either deliver higher performance or lower cost huge

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thanks to bill zoid for creating the videos used as a reference for the vrm

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portion of this video i've got those linked below if you want to get even

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more in depth than we did here and also thanks to jj from ASUS for offering some

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insight that only a motherboard expert can also let us know down in the

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comments if you guys want to see more turbo nerd edition videos and make sure

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to hit like this video is only able to go down a couple rabbit holes and there

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are so many more here there are also so many

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more high quality segways to our sponsor ifixit thank you to icefix for

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also comes with a lifetime warranty and i fix it has a bunch of awesome videos

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ifixit.com LTT if you like this video maybe check out our recent video on the

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semiconductor shortage that is making gpus nearly impossible to buy for

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a reasonable price at least it won't help you buy a GPU but at least it lets

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you go down that rabbit hole