Apple’s M1 Ultra chip within the Mac Studio is an absolute engineering marvel that pushes
the boundaries of performance by combining two M1 Max dies together using their new
UltraFusion die-to-die interconnect technology.
But I’ve doing a ton of research over the past week, looking into how Apple could take this
tech even further to create essentially an M2 Extreme chip which would essentially be
two Ultras stitched together for a total of 4 dies, creating basically the most
powerful chip you can find in a consumer PC today, breaking records left and right!
And in this video, I’m gonna explain exactly how Apple is gonna pull this
off in an easy-to-understand way, as well as how Apple is gonna be able to cool it down,
and also how much performance we can expect to squeeze out of it!
And yes, I actually paid $30 to download TSMC’s PDF on their new fifth-generation CoWos-S platform
with their brand new interposer which is used for UltraFusion so I could learn exactly how
all of this will work, so if you appreciate the effort, click subscribe to show your support!
Now if you watched my previous video on the M2 Ultra Duo, I based it on Apple’s 3D
chip stacking patents, but because of some MAJOR leaks that came in over the weekend,
I now believe it makes much more sense to use a different method,
with the 4 dies actually being joined side by side like in this mockup.
And before I get into explaining how it’s gonna work and showing you a bunch of
official Apple patent images from hours and hours of research,
I want to explain why I no longer believe the 3D stacked chip design is coming this year.
First of all, Mark Gurman was the #1 reason I believed Apple would go with the chip-stacking
route because it would actually be possible with the M1 Max dies which he said would end
up in a quad-chip Mac Pro with 40 cores, but in his recent PowerOn newsletter,
he updated his leak to include the likelihood of this quad-chip being based on the M2 Max
die instead which will actually be a 12-core chip!
And this is a BIG deal because the M2 Max could easily have two
die-to-die interconnects like you see in this image,
so Apple would just have to rotate them around to combine them into a quad-die chip.
And this actually makes the most sense because it’ll make it MUCH
easier to cool because you’ll have such a large package area
to place the heatsink onto instead of dealing with a dual-stacked die package.
But going even further, Majin Bu on twitter leaked an official Apple diagram showing not one,
but MULTIPLE UltraFusion interposers, and right there in the corner is exactly what it looks like,
a quad-die chip with UltraFusion connecting it vertically and horizontally.
And I was actually able to get some more information by the source who leaked this,
and he believes this quad-chip will be shipping within the new
Mac Pro by September, which makes a WWDC reveal extremely likely.
And the best part about this leak is that it perfectly matches up to Ross Young’s leak
for a new 27” Mini-LED Display that he believes will be shipping by September,
and he even told me that he expects it to be revealed at WWDC alongside the Mac
Pro, so I’m basically 100% sure about the Mac Pro coming at WWDC.
But getting back to that leaked diagram,
you’ll notice that there are multiple UltraFusion interposer chips with varying sizes,
and before I can explain how these are going to connect all 4 of the dies, you absolutely
must understand how the current M1 Ultra chip’s Ultrafusion works first, so let’s get into that.
Within that PDF that I purchased, there are some licensed images that I unfortunately
can’t show you, but thankfully, TSMC actually made some of them public, so check this out!
In this CoWoS-S progress slide, TSMC literally showed off an image of the M1 Ultra’s interposer,
which matches up to Apple’s marketing image of the M1 Ultra.
You have two large areas for the M1 Max dies, and 8 smaller areas for the RAM chips,
so everything is basically placed onto that interposer.
Now if you don’t know what an interposer is,
TSMC’s latest version can be up to 2500mm2 in size, and it actually features 5 layers
where there can literally be direct metal connections stitched through it.
And if you have a hard time imagining what the silicon interposer looks like,
imagine it like a big square block of jello consisting of 5 different layers which can
house a bunch of metal connections and signals between M2 Max dies and unified memory chips.
And to better explain it, I dug through Apple’s patents and I found this patent figure
which is actually flipped upside down. As you can see,
104A and 104B are actually two M1 Max dies, and this right in the middle
is quite literally 5 layers of UltraFusion metal stitchings connecting both of the dies together.
And if you don’t believe me when I say stitchings,
here’s an image I found showing how it works using another patent image from the side.
And the best part about the interposer is that it can also be used for routing
memory channels as you can see in this image of the Interposer sitting between the PCB substrate
which is the motherboard and the multiple chips, with 5 layers of interposer visible in the center.
But making things even better, there can also be TSV’s or through silicon vias, which can allow
connections to be made vertically from the chips directly into the PCB using the redistribution
layer which sends signals horizontally and allows connections to those TSV’s, which means that all
of the I/O like the Thunderbolt connections can actually travel down through the interposer and
into the motherboard instead of having to use a traditional connection like on the M1 Max.
And then finally, there can also be an active interposer where Apple can embed dedicated
chips and controllers to manage power usage and various signals and whatever else they want to do.
But the main point you need to know is that Apple starts with a chip package, then places
a silicon interposer onto it that consists of 5 layers and a redistribution fan out layer,
which is essentially what Apple is using to make those over
10,000 wired stitching connections between both M1 Max dies to create the M1 Ultra chip.
And now let’s get into how the quad-die chip is actually gonna work!
First of all, TSMC says their new high performance silicon interposer is limited to 2500mm2 in size,
which wouldn’t be enough for the massive quad-die M2 Extreme including all of the RAM chips,
but if you actually purchase the PDF, you get access to a big secret.
Apparently, they have something called quadruple mask stitching,
which literally allows them to take 4 interposer squares and stitch them together,
and in TSMC’s testing, there were no issues with stability by doing this.
And yes, I confirmed with the source that Apple
is in fact using quadruple mask stitching for the quad-die chip,
But now getting into how Apple is gonna stitch the 4 dies together,
the most interesting part is that Apple’s codename for this new chip is Redfern, which was apparently
the first high-end sportswear brand, potentially known for its sophisticated level of stitching.
And speaking of that stitching, a secret source has confirmed that there will be a total of
12 UltraFusion connections between the 4 dies, so that’s 3 connections per
die, which explains why the leaked diagram has three UltraFusions shown.
So I discussed all of this with tatech15 on twitter who shares my fascination for this
type of stuff, and he was able to draw up some diagrams showing how this will work.
As you can see, we have two Ultra chips on the left and the right, which already contain
UltraFusion connections between the top and bottom M2 max dies which are labelled Daisy1 and Daisy 2.
But as you can see, both of the top dies have two UltraFusion connections between them,
both a DaisyXL narrow and a Daisy XL wide, which was shown in that leak.
And if you’re wondering why there’s two of them, it’s probably to make sure there’s
enough bandwidth since you’re going from one M2 Ultra chip over to the other.
And then finally, there’s the DaisyXL sub 2 which doesn’t look like it makes sense
until you look at this little drawing, showing that this connection wraps
all of them together in a lower level of the interposer, kind of like in an L-shape.
And you’ll also notice a couple of dots
which are actually the controller chips within the active interposer.
And if this doesn’t seem like it’s possible, the source confirmed that each Max die will
be edited to have the paths integrated into the silicon to make all of those connections possible,
so it’s definitely gonna be much more complicated than it seems,
kinda of like this diagram with connections going all over the place!
And because of the combination of 12 total connections between all of the dies,
I have no doubt that Apple will be able to achieve essentially 2x scaling in terms of RAW
performance going from the Ultra to the Extreme. So if this new chip was based on M1 Max dies,
that would mean a Geekbench 5 multi-core score of around 48,000 points,
which would be competing with some of the best AMD Epyc server chips out there like the 7713
which has an MSRP of $7,000 alone and a TDP of 225W.
And the craziest thing of all is that the maximum TDP
on the new M2 Extreme should be around 120 watts, so half the power usage for the same performance!
But wait, those numbers are based on M1 Max dies,
and we’re almost certain at this point that the new Extreme chip will be based on the M2 Max,
which is rumored to be a 12-core chip instead of 10 like on the M1 Max.
And this means that the M2 Extreme will be even more powerful, especially since
we know that the M2 will at least be based on the A15 Bionic chip’s cores,
which as you can see in this image, are quite a bit larger than the ones on the A14.
And because of that, Tatech15 drew out a diagram showing that the M2 Max die should
be quite a bit larger as you can see with the dotted line, and this is very important because
it’s gonna give them a bit more room to fit memory channels and I/O around the top and left sides,
while packing the die-to-die interconnects on both the bottom and right sides which are in orange.
And this will be the secret to the M2 Extreme because they’ll be able to rotate
this new die and package them all up together just like we saw in that leaked Apple schematic.
And now with that said, there are two more topics to talk about, including how Apple
is gonna deal with the RAM and the PCI express slots, as well as how they’re gonna cool it!
According to Majin bu’s source, the DaisyXL connection that goes into the Sub2 layer
of the interposer can apparently access a separate memory controller
to access up to 1TB of memory, yes, I said 1 TB!
And he even gave us more details that currently, the 1TB of RAM has slower access times
than the older Xeon Mac Pro, which basically confirms that Apple is connecting extra RAM slots
directly to the M2 Extreme using that Daisy XL Sub 2 connection.
So what we’re most likely to see is the M2 Extreme coming
with 256GB of unified memory built onto the package and then a bunch of extra RAM slots
just so the real pros who need that much RAM can still pay for it.
However, I was reading through TSMC’s PDF document
and it mentioned that this new 5th generation of COWOS tech supports 8 stacks of HBM3 memory,
and the beauty of using HBM is it’ll allow them to save a TON of package space while
greatly increasing bandwidth and allowing for up to 1TB of memory on the package itself.
But I think this is gonna be way too expensive and the bandwidth will be overkill, so I think
Apple will stick to the traditional LPDDR RAM, especially since they can use the interposer
layers to route the RAM connections through the substrate which Hishnash on Twitter has confirmed
to me, and get creative with RAM placement like in these images that Hishnash mocked up,
or like in this example that I made a couple of months ago in this M1 Max Quad video.
And as for the PCIe slot situation
while I personally don’t think they’ll want to keep supporting third-party AMD graphics cards,
I do think there’s a very good chance Apple is working on their very own external GPU cards.
And the reason for my speculation on this is a little something called Lifuka, which was
a leaked code name for a dedicated GPU meant for the iMac Pro, and that makes sense because Lifuka
is an island in the kingdom of Tonga, which just so happens to be another codename for the M1 chip.
So I believe Apple’s engineers implied that this Apple Silicon GPU was meant to
be separated from the main SoC package, and I think we’ll be seeing it in the Mac Pro,
and I think it’ll be directly connected to the M2 Extreme using the DaisyXL sub 2 connection.
And now, finally, for the cooling part of the video,
since I don’t think they’ll be stacking M2 Ultra chips anymore, it’s gonna be a lot easier to cool.
So the first thing we need to do is figure out how much power
the M2 Extreme will take, which brings us back to the M1 Max, which according to Anandtech,
used a maximum of 92 watts when both the CPU and GPU were under a 100% load.
And keep in mind that this is totally unrealistic
and no regular workload will make this happen, but if we multiple 92 by 4 dies,
we get 368 peak maximum wattage that will need to be cooled for the worst-case scenarios.
And if that sounds like a crazy amount, it’s absolutely not because some of the
GPUs in Apple’s current Mac Pro use up to 500 watts of power and they’re being cooled
PASSIVELY, yes passively, with just a heatsink and the Mac Pro’s main 3 fans.
But going back to the Mac Pro’s announcement, Apples said that the CPU’s passive heatsink
can handle more than 300 watts of power, and not peak power, but sustained power!
So that means gives us a gap of 68 watts,
which I think Apple will have no problem cooling down for 2 different reasons.
First of all, the TSMC pdf that I purchased details two new thermal solutions, including
a ring-type package with die backside surface exposed for direct contact with heat sink,
which is something Apple has already used on the M1 Ultra
in detailed public patents with great success.
And they also mentioned a new TIM or thermal interface material which allows them to bond
the heatsink plate directly over the chips for 100% coverage, allowing for the least
amount of thermal resistance possible for maximum heat transfer into the heatsink.
And now the second reason is that Apple has already confirmed
that they’re using a new much heavier COPPER heatsink in the Mac Studio to cool down the M1
Ultra chip, so this basically confirms that Apple will be using copper in the Mac Pro as well,
which will make it much easier to cool down 368 watts of power from the M2 Extreme.
And to finish off this video, I once again think the Mac Pro will be revealed at WWDC
and ship in September, and I think it’ll either come in the same exact chassis as the current
Mac Pro, or they’ll end up shrinking it down a bit, potentially like this.
So with that said, hopefully you enjoyed this video,
and if you did, go ahead and give me your thoughts on all of this down in the comments
below and click that circle above to subscribe because we’re about to begin massive amounts of
Mac Studio testing this week! So thanks for watching and we’ll see you in the next one!