 This heat sink right here, pointless. Four RAM slots, you only need two of them. And why is there a PCI Express slot that has SLI? No one uses it. Why the heck does everybody want all of this? It's because nobody actually knows what motherboards are and how they work. So here it is, to the best of our ability, how motherboards work. So buckle up nerds, line is on vacation and we're not holding back. Just like I can't hold back this segue to our sponsor, iFixit. Do you like to repair your own electronics instead of having to spend hundreds on expensive replacement or repair services? Learn more about iFixit's essential electronics toolkit at the end of this video. ["Extraordinary by iFixit"] Computer power supplies output 12 volts. If you apply 12 volts to a CPU, it'll look something like this. Hmm. Suboptimal for sure. Ooh. Ha ha ha ha. Suboptimal for sure. To avoid the magic smoke, we need to take that 12 volts and step it down to something more like 1.2 volts. And this is exactly the job of voltage regulation modules, the VRMs that overclockers talk about so much. The basic circuit consists of two MOSFETs, which in this situation are basically just fancy switches, an inductor and a diode. This first switch closes, which then charges this inductor, converting the electricity into a magnetic field. The voltage the CPU gets depends on how long this switch is closed, but the instant it is opened, the voltage to the CPU begins to drop. Kind of like a, I don't know, a drain. So this is where that diode here is very important. If both switches are open while the inductor is charged, it's magnetic field will collapse and pop goes your CPU. But the diode is highly inefficient. So it's important to get the second switch closed as soon as possible to avoid creating any unnecessary heat. If you're paying attention, you might've noticed a problem here though. Although the voltage will be bouncing around what the CPU is asking for, there are a lot of spikes, not great for stability. And there are two ways to remove this. The first is to just increase how fast the MOSFET switches. On motherboards, this is normally done at about 300,000 times per second, but even then the voltage can fluctuate more than the CPU wants. And it isn't practical to try switching a whole lot faster than that. Every single time the MOSFET switches on or off, it generates a bit of heat and above about 150 degrees Celsius, the MOSFET's gonna die. So if we want cleaner power, we don't need faster MOSFETs, we need more of them. The circuit we have here represents a single phase, another term that overclockers love to use so much. So by adding another phase, we can roughly double how clean our power is with the benefits of additional phases scaling roughly linearly from there. The number of phases in your motherboard is normally shown as a number like eight plus two, which means eight phases for the CPU and two dedicated for the RAM. Let me put this away. Multiple phases also have another benefit. Say your CPU requires 100 amps to run. With a single phase, all 100 amps would have to go directly through those components, but with two phases, only 50 amps would go through each phase, meaning lower rated and thus cheaper components can be used. You might be tempted to think then, well, more phases equals more better, which is true to a point. However, as you add more phases, controlling them can get more difficult, which translates into the VRM's being less able to respond to changes in voltage. Like everything then, there are trade-offs between having less phases with higher quality components or more phases with lower quality components. This does create a rather odd situation though. High-end motherboards normally have the most phases and the highest efficiency components, which means the VRM temperatures should be really low, but these motherboards also have the best VRM heat sinks. Why? Purely to look cool. Mid-range boards might actually need good VRM cooling, but for anything other than extreme overclocking, a high-end board would probably be fine with no VRM heat sinks at all. It's similar to how you'd be fine without a shirt from lttstore.com, but definitely look cooler with one. Now that the CPU has power, how does it talk to the rest of the system? This copper wire represents how far an electric signal can travel in a nanosecond. Oh, everything falls. At 5,000 megahertz, your RAM can send data every 0.2 nanoseconds. In that amount of time, an electric signal can travel this far. So then this is physically impossible. RAM makers have lied to you. Although on your RAM stick, in the BIOS and in Windows, your RAM will say it's running at 5,000 megahertz or whatever, in reality, it's completing 5,000 mega transfers per second. What's the difference? Well, since it's DDR or double data rate RAM, transfers are done on both the beginning and the end of each individual hertz. This means the sticks are actually running at 2,500 megahertz, which is why if you've ever looked in CPU-Z, the RAM shows up as half of what everything else claims it is. Depending on what you wanna do with your motherboard, knowing how the CPU and the RAM connect can be important. Like, have you ever wondered why the manual always says to put the RAM in the second and the fourth slots on your motherboard? For this example, we'll be looking at a CPU with dual RAM channels. This is the most common configuration for consumer CPUs, but the same basic principles apply to workstations or server processors with more channels. The absolute best case scenario for a dual channel CPU is to simply have two RAM slots. PCB traces go directly from the controller to the RAM stick with nothing else in the way. This is why ASUS's top tier gaming boards only have dual slots. And also why some ITX motherboards like this one can punch way above their weight class when overclocking RAM. Moving on to motherboards with four RAM slots. Here you have two main options, T topology and daisy chaining. T topology is when the traces to each RAM stick on a channel are the same length, which can be great for running all four slots at relatively high speeds. But if pure speed is what you're after, then daisy chaining is the way to go. With a daisy chain motherboard, the traces basically just go to one slot and then continue on to the next one. This can cause the speeds to be lower when all four slots are used. The timing differences between the two sticks has to be figured out by the controller. But it also means with only two sticks, you can run them at nearly the same speed as if there are only two slots. Now it is important to use the correct slots though. If an electric signal goes through a wire and the wire suddenly ends with nothing connected to it, like this. The signal can reflect back, creating noise in the circuit. By putting the RAM sticks in slots two and four, the traces end at the RAM stick, reducing noise in the circuit and allowing for higher speeds. So basically before you buy RAM, check if your motherboard has daisy chain or T topology, since it determines if you should get two higher capacity sticks or four lower capacity ones. With higher capacity DIMMs getting cheaper and cheaper, it now would make sense for most gaming motherboards to only have two RAM slots optimized to go as fast as possible. Our contact at ASUS agreed, but said way too many people will complain that they can't upgrade their memory in the future, even if statistically very few people actually will do that. But even without topologies and slots, like if you had the CPU right next to the RAM and used gold traces or whatever for the perfect signal, there would still be something else holding you back, the memory controller on the CPU. Everyone has accepted at this point, there's a Silicon lottery and some CPUs will naturally be able to clock higher at lower voltages. But the same applies to the memory controller on the CPU. Your luck in the Silicon lottery can sometimes have the biggest effect on how fast your RAM runs. The CPU and RAM are now working, but we still need to be able to connect things like the GPU storage and peripherals. In the past, this would be done through the chipset with the Northbridge taking care of PCIe and memory, while the Southbridge handle IO storage, audio, USB, you know. On modern motherboards though, the memory and some PCIe lanes are connected directly to the CPU, while a chipset handles everything else, which simplifies the layout and allows for lower latencies. Losing a whole chip is big, but what's even more shocking is just how fast PCIe has become. With PCIe 4.0, a one lane slot can do up to two gigabytes per second, and a 16 lane slot is able to transfer a staggering 32 gigabytes per second. That's close to the speeds of DDR4 RAM. How the heck can they pull this off? Simple, very expensive PCBs. Previously it was possible for lower end motherboards to have only like four or so layers, but now in order to get PCIe 4.0 levels of signal quality, eight to 12 layer PCBs are basically a requirement. Given every two layers can come with a 20 to 30% cost increase for the PCB, the insane prices of modern motherboards start to make a bit more sense, even if the majority of users will struggle to saturate a PCIe 3.0 connection, let alone 4.0. So you might've noticed a bit of a theme here. One of the most difficult parts of designing a motherboard isn't creating the best possible product, but carefully balancing the actual value and perceived value. Like this motherboard right here supports SLI, has massive VRM heat sinks, it has four DIMMs because those are things that people expect. It probably would be better for the majority of users if there were just two RAM slots closer to the CPU. One PCIe connector and you know, the price of this one down here was turned into better traces. And okay, the VRM heat sink, it looks pretty cool. And I wouldn't want to give it up. But at least I know that that's a trade-off that I'm making. And hopefully in the future, we can be more open to crazy motherboard designs that either deliver higher performance or lower cost. Huge thanks to Bill Zoid for creating the videos used as a reference for the VRM portion of this video. I've got those linked below if you wanna get even more in depth than we did here. And also thanks to JJ from Asus for offering some insight that only a motherboard expert can. Also, let us know down in the comments if you guys want to see more Turbo Nerd edition videos and make sure to hit like. This video is only able to go down a couple of rabbit holes and there are so many more here. There are also so many more high quality segues to our sponsor, iFixit. Thank you to iFixit for sponsoring today's video. Their iFixit Essential Electronics Toolkit is a great basic kit for new users. It gives you what you need for the most essential electronic repairs. It has a compact size, includes the most popular precision bits and it's held together with a high density foam that you can throw around without any of the bits falling out. It also comes with a lifetime warranty and iFixit has a bunch of awesome videos to show you how to take apart your device and stuff. Get it today at ifixit.com slash LTT. If you like this video, maybe check out our recent video on the semiconductor shortage that is making GPUs nearly impossible to buy for a reasonable price at least. It won't help you buy a GPU, but at least it lets you go down that rabbit hole.