Engineering: What qualities make something great or a mess? *spawn from XBox One X*

[function]

It's pretty common on GDDR5 graphics cards that memory devices on corners are tilted. It's a somewhat weird tilt on that one chip there in the X, but I doubt it's worth putting too much thoughts on why that is without knowing more of what the H/W engineer(s) doing the layout was thinking. You don't have to match trace lengths (at least within reason, I assume ) with GDDR5, that's why you can squish the memories a lot closer to the ASIC compared to DDR3 used in the original Bone/S.

Yeah, I'm used to seeing corner memory chips angled, but I've never seen this before. They aren't actually angled, they're staggered in distance from the soc, each one changing by a small amount.

Given that you don't have to match trace lengths there has to be a reason, be it power or timings or interference or whatever.

I don't think the render from E3 2016 showed this, so it might be something implemented during the physical implementation of the design (or maybe it was to hide SecSauce ;o ).

 

[mpg1]

It probably has to do with the amount of space required between each memory chip and the SoC (cooling factored in?). The corner memory chips are closer to the ones that are offset... probably required them to be out further than the others.

 

[Grall]

They aren't actually angled, they're staggered in distance from the soc, each one changing by a small amount.

Hm, I didn't notice the staggering until you mentioned it here. Good call. No idea why that is - especially as the vertical row of chips don't seem to stagger at all. Maybe some artifact of automated layout striving to keep traces roughly the same even though it's not strictly necessary...?

If one looks at the outermost corners top and bottom of the notch in the mobo that's seemingly for the 2.5" HDD, there's some electrical components (I assume; seeing as they're soldered onto the mobo with rather substantial metal tabs) sitting at the edge of the board that looks almost like a little pinhole camera thingy, but I don't think that's actually the case. What are those, and what do they do?

 

[Globalisateur]

Can you please share what portions make it a mess on the Xbox One X motherboard, is it the power regulation, the overall layout, or the excessive number of surface mount device components? To this layperson, the 4Pro board looks "cleaner" / less cluttered. I hope that makes sense.

This.

Why are there so many additional components on the Xbox One X?

I eagerly await the answer.

 

[Scott_Arm]

I'm not an electrical engineer, never did pcb layout. But I did study electronics. I'm genuinely curious about where people's impressions about pcbs comes from. I'm surrounded by pcbs vastly more complex than these on a daily basis. I've never had an eye for what is a good or bad layout just by looking at a pcb.

 

[iroboto]

This.

I eagerly await the answer.

Arm chip on ps4 is the most noticeable device that could replace so many components.

 

[function]

I wonder if all the mobo mounted caps and resistors allows Mr Hovis to manually solder configurations on for each SoC?

Seems unlikely, but I guess you could actually program the robots to read a database as they are assembling a specific database and assemble accordingly...

 

[AlNom]

How does the slim mobo compare?

 

[iroboto]

How does the slim mobo compare?

Still busier than PS4. I think it's already posted above. I'm not sure if that was the S mistaken for the OG board. If not they look pretty close

https://www.ifixit.com/Teardown/Xbox+One+S+Teardown/65572

 

[BRiT]

How does the slim mobo compare?

The xbox one slim is nearly the same as the xbox one day-one motherboard, only noticable difference is the front versus side usb mount and the backside ports. The major components are aligned into the same general locations.

Or did you mean the 4Slim motherboard?

 

[Scott_Arm]

Pretty much everyone that does PCB layout uses one of a few software packages from Mentor, Cadence or one or two others. Unless Sony has something in-house that they've built over the years. I'd be surprised if they did. Assuming they're using Mentor or Cadence, I don't think there's much advantage they'd have over any other company that's hiring experienced engineers. The individual talent that one company has over another may be greater though. Maybe the Sony team really has some layout wizards. I do know that layout is considered very difficult, and some people create better layouts than others.

I can't find any details on how many layers the PCBs of each console have. That could lead to differences in surface routing that could make one pcb look cleaner/busier. It does look like the Xbox PCBs have more components, and I'm not going to try to guess why. Some are going to be related to Kinect, HDMI in, NAND.

I'm still not sure that busyness or messiness are particularly good metrics for anything. Signal integrity is everything, I'd guess. There is an argument to be had about cost, but most of those small smd components cost next to nothing. I'm just not sure where there appears to be such a disparity in the number of extra caps, resistors.

 

[mpg1]

I'm curious...did the people bringing up that they "didn't like the look" of the X1X motherboard have any electrical engineering experience? What exactly is this discussion based on?

 

[AlNom]

I'm just not sure where there appears to be such a disparity in the number of extra caps, resistors.

Potentially (*ahem*), they use more components in parallel as opposed to a singular equivalent. There are pros/cons to either way.

I don't know if Sony's devkits are capable, but Scorpio kits do also have the option of higher-than-retail performance, so they may not be as finely tuned to the single spec.

 

[iroboto]

people bringing up that they "didn't like the look" of the X1X motherboard. What exactly is this discussion based on?

Reverse these two sentences and your answer is found.

I'm not going to say no one is qualified to speak to it, but chances that anyone here is a mobo layout engineer for consoles that can provide reasonable insight as to why boards can be laid out specific ways is pretty slim. Even harder to identify why the board are so different, but the two consoles don't offer the same features nor do they use the same OS, so there is a lot to account for.

 

[AlNom]

If we're only going by visuals/components, one would probably want to also compare to motherboards of all varieties - mobile and laptop and desktop and GPUs.

Alas, what constitutes "good" is perhaps better described as "elegant" when clearly Scorpio isn't blowing up due to "bad" engineering.

 

[dobwal]

If we're only going by visuals/components, one would probably want to also compare to motherboards of all varieties - mobile and laptop and desktop and GPUs.

Alas, what constitutes "good" is perhaps better described as "elegant" when clearly Scorpio isn't blowing up due to "bad" engineering.

Personally I don't care if a console's motherboard looks like it was thrown together by Macgyver locked inside a junkyard as long as it's functional, reliable, quiet and not a threat to burn down my house.

If there is no one here to enlighten us to technicalities of PCB layouts. What's the point?

Sony does a much better job at a cleaner layout when it comes to consoles, but the Xbox one's motherboard in comparison to other devices like your average laptops (including ones from Sony) looks par for the course.

Sony's console MBs looks more akin to motherboards you find in consumer electronics like TVs or bluray players which makes a lot of sense because that's Sony DNA while MS looks like something powering a pc device which is MS's DNA. Designs powered by differing expertise is likely driving the difference.

 

[MrFox]

For those asking why this thread even exists, let alone in the technical section...

I wrote an opinion about the cooling being as ideal as physically possible (which would require an incredible expert to validate, and warrant discussion, I'd need a phd to even make that statement, I'm seriously unqualified, why did nobody quote me and ask me how I could possibly know that?), and added a short unimportant one about the final board not looking better than previous xboxes, because of the new pictures.

It was more intended as "canary" post.

Second post was about the way mods are selective about rules, based on recent events which I suppose only the mods know. There were many ways to deal with that post, and as expected it was immediately spun off to protect the Safe Space. A six word footnote produced this. "the motherboard is still a mess" is now rewritten dramatically as "trash" in the title.

Anyway... I might as well say something that sounds intelligent on the surface before this thread is closed.

I think the power delivery area difference is related to sony using fully integrated 1MHz vrms on each phase. It might allow them an easier filtering of noise, ripple and transients. Much less vrm glue part compared to MS who might be using the NCP42xx suggested implementation, which is more discreet stuff. Only a few large cap (the black rectangles) for main ripple, and a few tiny MLCC directly under the SoC to filter transients (two sizes for two frequency bands?). Much smaller main inductors (small grey rectangles) than xbox might indicate sony is using the vrms at the full 1MHz, while MS would be much lower in the 300-500. Why MS needs a huge array of intermediary MLCC is unclear, it could means the switching edge might not be clean enough, massive transients is often a compromise to get fast switching edge for high efficiency avoiding having to cool the mosfets at all. But you pay with needing much more high freq filtering, which those small MLCCs are ideal for. Larger ones suck at high freq.

It's counterintuitive, but having hundreds of discreet parts is a cost and development time compromise. It costs less to use discreet parts and generic chip than an exact purpose part. The more integrated, the more special purpose the silicon is. I think PC motherboards do this often because they are short runs with new models every year, modular features and a dozen models. The time between getting the chips from intel and the launch window is horribly short.

Connectors and cables everywhere, vertical standard sata, electrolytic caps and large connectors like this is 2005. Finally got the trick of making the board L shaped for the drive, didn't figure out to put the connector right there. Cable goes around from the wrong end as if engineers didn't talk to each other. Most companies moved to high pitch thin cables. It looks like a prototype model.

Okay this should be a big enough wall of text... Now it's time for Gran Turismo Sport!

 

[Rikimaru]

Just like MS being a software and OS company, has the edge with their OS and more recently their API via their DX12 implementation on XO.

I do not think this is true either. Both Windows 10 PC and xbo OS are glitchy mess with awful design.
PS4 graphics API was good from the beginning.

I've made a thread about overall console engineering, but it did not go well.
https://forum.beyond3d.com/threads/console-engineering.60051/

 

[Scott_Arm]

...
I think the power delivery area difference is related to sony using fully integrated 1MHz vrms on each phase. It might allow them an easier filtering of noise, ripple and transients. Much less vrm glue part compared to MS who might be using the NCP42xx suggested implementation, which is more discreet stuff. Only a few large cap (the black rectangles) for main ripple, and a few tiny MLCC directly under the SoC to filter transients (two sizes for two frequency bands?). Much smaller main inductors (small grey rectangles) than xbox might indicate sony is using the vrms at the full 1MHz, while MS would be much lower in the 300-500. Why MS needs a huge array of intermediary MLCC is unclear, it could means the switching edge might not be clean enough, massive transients is often a compromise to get fast switching edge for high efficiency avoiding having to cool the mosfets at all. But you pay with needing much more high freq filtering, which those small MLCCs are ideal for. Larger ones suck at high freq.

It's counterintuitive, but having hundreds of discreet parts is a cost and development time compromise. It costs less to use discreet parts and generic chip than an exact purpose part. The more integrated, the more special purpose the silicon is. I think PC motherboards do this often because they are short runs with new models every year, modular features and a dozen models. The time between getting the chips from intel and the launch window is horribly short.

Connectors and cables everywhere, vertical standard sata, electrolytic caps and large connectors like this is 2005. Finally got the trick of making the board L shaped for the drive, didn't figure out to put the connector right there. Cable goes around from the wrong end as if engineers didn't talk to each other. Most companies moved to high pitch thin cables. It looks like a prototype model.

Okay this should be a big enough wall of text... Now it's time for Gran Turismo Sport!

Good post - the part about vrm especially.

 

[iroboto]

I wrote an opinion about the cooling being as ideal as physically possible (which would require an incredible expert to validate, and warrant discussion, I'd need a phd to even make that statement, I'm seriously unqualified, why did nobody quote me and ask me how I could possibly know that?), and added a short unimportant one about the final board not looking better than previous xboxes, because of the new pictures.

It was more intended as "canary" post.

Your commentary on cooling didn't need to be validated. It's using the best known cooling system available for the market for it's form factor. If it was custom cooling designed to be better than market available cooling, one would have to back those statements up.
There's also nothing particularly confusing about cooling either. You need as much cooling as there is heat.

Most people can't look at a circuit board and tell what each piece does. Hell most people can't read the values of a resistor even though ti's labelled, let alone be able to tell what ICs do what just by looking at a picture of it. You'd need white papers for that and you'd need to be able to read the chip name to accomplish that.

That's why commentary on motherboards, or electronic boards itself is insane. At least for me. I leave mother boards as is as long as they are operating well within their desired parameters.