Tell me more ×
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It's 100% free, no registration required.
up vote -4 down vote favorite

I am building my own laptop, and found out that the motherboard for a laptop has to be designed based on the case. So, I am designing my own motherboard. The thing is, I have no idea how a motherboard works. (I know about transistors, diodes, resistors, capacitors, etc.)

My questions are:

  1. How do I interface everything together (The cpu, graphics cards, ram chips, etc.),
  2. What FREE software would you reccomend for designing it (I'm currently using DesignSpark),
  3. What manufacturer would you recommend for getting a quantity of one built at a fairly cheap price? (I have found manufacturers offering 2 or 3 for 400-500 dollars, but I just want one.)

I would like a link to a good and (fairly) easy to understand tutorial.

share|improve this question
12  
If you don't know how a MB works you can't design one. Better go do something else. – stevenvh Apr 15 '12 at 15:18
1  
One will probably cost you twice as much as two. NRE is the same. – Federico Russo Apr 15 '12 at 15:19
3  
An MB brings a few aspects of electronics with it that you probably never heard of before. How are you going to debug it? Start with something simpler. – jippie Apr 15 '12 at 15:21
12  
A PC motherboard on a breadboard! No, don't close this question, this is gonna be fun! – stevenvh Apr 15 '12 at 15:31
2  
It's so obvious that you don't have a clue of what you're talking about. Nobody can make a digital design with the complexity of a MB work at 4GHz on a breadboard. Nobody. – stevenvh Apr 15 '12 at 15:36
show 22 more comments

closed as not a real question by stevenvh, clabacchio♦, Leon Heller, Olin Lathrop, Kortuk♦ Apr 15 '12 at 22:04

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.

4 Answers

up vote 7 down vote

I hate nay-sayers more than anyone, and I'm all for undertaking difficult projects.

BUT

Designing and building a motherboard is Extremely difficult. Even if you already had great EDA software, and even if you already knew how to wire up the chips, the designing, building and testing process is about as hard as it gets.

It's a bit like asking: "I'm trying to do my own moon mission. How do I make gunpowder?"

share|improve this answer
2  
Or: "I'm trying to do my own moon mission. What office software do I need?" – stevenvh Apr 15 '12 at 16:18
4  
Yeah, "Is there any open-source moon software around?" – Rocketmagnet Apr 15 '12 at 16:19
2  
Your own moon mission: en.wikipedia.org/wiki/OpenLuna – jippie Apr 15 '12 at 20:28
1  
@jippie Now I've seen everything. – Rocketmagnet Apr 16 '12 at 11:39
@stevenvh, I feel like it is backwards, it is more like saying I have the software for designing rockets, I know how gunpowder explodes, how do I go to the moon? – Kortuk♦ Apr 17 '12 at 2:50
up vote 5 down vote

If your goal is to design a modern PC, forget it really.

Modern chips interface with busses like PCI express or high-speed differential busses. You can't breadboard this up, no way. Frequencies are from 100MHz up to several GHz. A breadboard will probably 'fall apart' at a couple of MHz (I can't even get my serial port to work at 3MBaud on the heavily used breadboard I got). Even routing boards with these speeds requires a lot of knowledge and know-how.

Other than that, the exact pin-outs of some chips are hard to get. Where are you going to find the pin-out of a chipset? How are you going to prototype this? Your question of an one-off motherboard an fairly cheaply is a contradiction itself. A one-off is not cheap, never will.

The DesignSpark toolkit is hilarious for any PCB more than 2 or 4 layers. You know modern computer motherboards use atleast 8 layers? There are some figures of like 12 or 16 I believe. You also know they are designed with multi-million EDA tools to verify signal integrity, PCB design, etc.? You also know that they are not designed by one person? As a one-off these costs not hundreds to produce, probably thousands each (may even be underestimated). Only in production where ten of thousands are produced, they become affordable.

Anyway, if you intend to learn about the workings of a motherboard you probably should look the theory up of high-speed PCB design such as differential routing pairs and multi-layer routing, multi-phase switch-mode power supplies, phase locked loops, BGA's, power supply decoupling, seperate/local ground planes, and a bunch of other stuff. Most of this what I called can just be applied to PCB design. Th schematic is just figuring out what the pinouts are, how chips should be interfaces, power supply requirements and practical production requirements. As I said, pin-outs of some chips or the workings can be proprietary (however I do know you can find the Intel CPU's pin-outs on the internet).

Look, if we all could do this you would see projects all over the internet with people 'hey, that guy stuck a Celeron on his line follower robot!'.

share|improve this answer
Can you suggest a program to use, then if DesignSpark isn't very good? – Him Apr 15 '12 at 15:45
I am not saying DesignSpark is any good, I am just saying it's not good for the purpose of designing complex boards which a high-speed design requires. It will probably fit the bill for hobbyist use, just like Eagle, TinyCad, KiCad and a bunch others do. 'Proffesional tools' would be like Altium designer, Mentor graphics or Cadance Allegro.. but they are very hard to use and very very expensive. – Hans Apr 15 '12 at 15:46
What about AutoCad electronics? – Him Apr 15 '12 at 15:48
AutoCad is for mechanical engineering, so I figure the electronics edition is for wiring up machines and industrial installations (relays, PLC's and big stuff). – Hans Apr 15 '12 at 15:49
What do corporations like Intel use to design motherboards? – Him Apr 15 '12 at 15:50
show 3 more comments
up vote 5 down vote

You should learn what's realistic and what's not, and know your limitations.

You come up with a price of 400 - 500 dollar for a couple of PCB's, but you don't seem to realize that these are just the PCBs, without any components, and without the cost of the design (which you are going to do). That's what an 8 to 12 layer PCB the size of a motherboard costs. You don't know that.

You don't know what components or subsystems a motherboard contains, you only know its mechanical dimensions (fit inside your DIY laptop). You have no clue about design tools: DesignSpark doesn't even get you started. You don't know why that is.

You don't know how to start a high-speed design, and what kind of pitfalls you'll encounter. I mentioned impedance matching, you don't know what that is and why it's important. You don' know what a transmission line is.

You want to breadboard the design, but you don't realize that you can't even make the system work that way, not even at 100MHz, let alone 4GHz. If you would be able to make a digital design at 100kHz you don't know how to scale it to 4GHz.

You don't know that none of the components and subsystems is fit for breadboarding. (Do you know what an LGA is?)

Do I need to go on?

share|improve this answer
up vote 1 down vote

This might help you a little bit. It will give you some idea of how much work goes into laying out a motherboard type PCB. But remember that this guy already knows all about high speed design, impedance matching, power supply distribution for high speed ICs, etc.

YouTube: Extreme PCB layout - DDR3 Interface

share|improve this answer
I'll have the monitor this guy is working with. – jippie Apr 15 '12 at 20:33
@jippie Holy smeg .... The resolution. I hadn't noticed. – Rocketmagnet Apr 15 '12 at 20:36

Not the answer you're looking for? Browse other questions tagged or ask your own question.