The last I checked, AMD was outperforming Apple perf/dollar on the high end, though they were close on perf/watt for the TDPs where their parts overlapped.

I’d be curious to know if this changes that. It’d take a lot more than doubling cores to take out the very high power AMD parts, but this might squeeze them a bit.

Interestingly, AMD has also been investing heavily in unified RAM. I wonder if they have / plan an SoC that competes 1:1 with this. (Most of the parts I’m referring to are set up for discrete graphics.)

The M4 Pro is 56% faster in ST performance against AMD’s new Strix Halo while being 3.6x more efficient.

Source: https://www.notebookcheck.net/AMD-Ryzen-AI-Max-395-Analysis-...

Cinebench 2024 results.

That’s a laptop part, so it makes different tradeoffs.

Somewhere on the internet there is a tdp wattage vs performance x-y plot. There’s a pareto optimal region where all the apple and amd parts live. Apple owns low tdp, AMD owns high tdp. They duke it out in the middle. Intel is nowhere close to the line.

I’d guess someone has made one that includes datacenter ARM, but I’ve never seen it.

High TDP? You mean server-grade CPUs? Apple doesn't make those.

True, but these "Ultra" chips do target the same niche as (some) high-TDP chips.

Workstations (like the Mac Studio) have traditionally been a space where "enthusiast"-grade consumer parts (think Threadripper) and actual server parts competed. The owner of a workstation didn't usually care about their machine's TDP; they just cared that it could chew through their workloads as quickly as possible. But, unlike an actual server, workstations didn't need the super-high core count required for multitenant parallelism; and would go idle for long stretches — thus benefitting (though not requiring) more-efficient power management that could drive down baseline TDP.

Oh you. mean Threadripper. I thought you were talking about Epyc.

Anyway, I don't think it's comparable really. This thing comes with a fat GPU, NPU, and unified memory. Threadripper is just a CPU.

The GPU and NPU shouldn't be consuming power when not in use. Why shouldn't we compare M3 Ultra to Threadripper?

Indeed. The M3 Ultra is in the midrange where they duke it out. Similarly, for its niche, the iPhone CPU is was better than AMD’s low end processors.

Anyway the Apple config in the article costs about 5x more than a comparable low end AMD server with 512GB of ram, but adds an NPU. AMD has NPUs in lower end stuff; not sure about this TDP range.

How is that comparable? On-package RAM is lower latency and higher bandwidth and also much more expensive than external DDR5 sticks.

Isn't the rack-mounted Mac Pro supposedly "server-grade" (https://www.apple.com/shop/buy-mac/mac-pro/rack)?

At least judging by the mounts, they want them to be used that way, even though the CPU might not fit with the de facto industry label for "server-grade".

Server grade CPUs. I thought he was referring to Epyc CPUs.

The rack mount Mac Pro doesn't really make sense for a data center. It's 5U high, which is much too big for a data center. It doesn't have standard server features like redundant power supplies.

The only use case I can think of is for audio workstations, where people have lots of rack mount equipment, so you can have everything including the computer in the rack. But even for that use case it's quite big.

> You mean server-grade CPUs? Apple doesn't make those.

Right.

It is coming up because we're in a thread about using them as server CPUs. (c.f. "colo", "2U" in OP and OP's child), and the person you're replying to is making the same point you are

For years now, people will comment "these are the best chips, I'd replace all chips with them."

Then someone points out perf/watt is not perf.

Then someone else points out some M-series is much faster than a random CPU.

And someone else points out that the random CPU is not a top performing CPU.

And someone else points out M-series are optimized for perf/watt and it'd suck if it wasn't.

I love my MacBook, the M-series has no competitors in the case it's designed for.

I'd just prefer, at this point, that we can skip long threads rehashing it.

It's a great chip. It's not the fastest, and it's better for that. We want perf/watt in our mobile devices. There's fundamental, well-understood, engineering tradeoffs that imply being great at that necessitates the existence of faster processors.

  It's a great chip. It's not the fastest, 

It has the world's fastest single thread.

I can't quite tell what's going on here, earlier, you seem to be clear -- c.f. "Apple doesn't make server-grade CPUs"

Correct. But their M4 line has the fastest single thread performance in the world.

According to what source? Passmark says otherwise[1]. The fastest Intel CPUs have both a higher single thread and multi thread score in that test.

[1] https://www.cpubenchmark.net/singleThread.html

Passmark shows the M4 chips slower than the M3, so something weird is going on. Geekbench 6 has the M4 well ahead of Intel and AMD, with the M3 about 25% slower like you'd expect: https://www.cpu-monkey.com/en/cpu_benchmark-geekbench_6_sing...

I keep seeing people repeat incorrect rhetoric about Apple hardware, like this example.

There are nice things that Apple has, but as you can see there is significant reality warping going on.

Why does it persist?

Never change hn, can't criticise apple here.

Passmark is an outdated benchmark not optimized for Arm.

I think that is much too hand-wavy regarding the performance differences.

Both Passmark and Geekbench are aggregates of a variety of tasks. If you dig into the individual tests that constitute this aggregate score, you will find different platforms perform better, or worse, on certain tests than others. I would wager that, for many applications, only a subset of these tasks are relevant to the performance of the application, yet such benchmark suites distil out all nuance into a single value.

Here is a personal anecdote. I have tried running CASTEP (built from source), a density functional theory calculator, on both an M1 Max MacBook Pro [0], and on a Ryzen 7840HS Lenovo laptop [1]. A cursory glance at those Geekbench results linked might make you expect that the performance is roughly equivalent, but the Ryzen outperforms the Mac by about 4x, a huge difference.

What happens if we try and dig into any particular benchmark to explain this? If you click on any particular benchmark in the Geekbench search lists, you will see they test things like "File Compression", "HTML5 Browser", "Clang". Which of these maps most closely to the sorts of instructions used in CASTEP? Your guess is as good as mine.

If anything, I would say Passmark is quite a bit less abstract about this. Looking at the Mac [2] and Ryzen [3] Passmark results, you can see the Ryzen outperforms the Mac by about 2x on "extended instructions", which appear to involve some matrix math, and also about 2x on "integer math". The Mac, meanwhile, appears to be extremely good at finding prime numbers, at over 3x the speed of the Ryzen. Presumably the Ryzen's balance of instruction performance is more useful for DFT calculations than the Mac's, which perhaps is weaker in areas that might matter for this application, but stronger in areas that might matter for others.

Of course, optimization is likely a component of this. How much effort is put into the OpenBLAS, MPI, etc, implementations on aarch64 darwin vs. x86-64 linux? This is a good question. It is, however, mostly irrelevant to the end consumer, who wishes to consume this software for use in their further research, rather than dig into high-performance computing library optimization.

[0] https://browser.geekbench.com/search?q=7840hs

[1] https://browser.geekbench.com/search?q=m1+max

[2] https://www.cpubenchmark.net/cpu.php?cpu=Apple+M1+Max+10+Cor...

[3] https://www.cpubenchmark.net/cpu.php?cpu=AMD+Ryzen+7+PRO+784...

This is my experience as well. Geekbench heavily favors the type of workload that runs best on Apple hardware (those tends to be general case, most likely to be used by the mass) but in practice if you have complex software to run your experience will not match the bench numbers.

I think PassMark is more honest as well, because it just gives scores for calculation throughput instead of specific tasks. It more closely matches what experience you will get if you have a varied load.

But since it's Apple we are talking about, their users just want to think they have the best and that's all that matters.

PassMark is "more honest"? It represents a varied load??? No, sorry, it's just not good. Seriously, read their own documentation.

https://www.cpubenchmark.net/cpu_test_info.html

Right from the top it's amateurish stuff: their idea of an integer benchmark to measure "raw" CPU throughput (whatever that means) is to make a bunch of random ints and add/subtract/multiply/divide them.

Very few programs do a high volume of either integer multiply or divide. And when they do, they generally aren't doing it on random numbers. This is the kind of thing which gives synthetic benchmarks their highly deserved bad rep. It might be even worse than Dhrystone MIPs, and believe me, in benchmark nerd circles, that is a fucking diss.

If you look up Geekbench's docs, you'll find that it's all about real-world compute tasks. For example, one of the int tests in their suite is to compile a reference program with the Clang compiler. Compilers are a reasonably good litmus test of integer performance; they heavily stress the CPU features most responsible for high integer performance in this day and age. (Branch prediction, memory prefetching, out-of-order execution, speculation, that kind of thing.)

You claimed that PassMark reflects "complex" software, and Geekbench doesn't. However, I would be willing to bet that Clang alone is far more complex than all of PassMark's CPU benchmarks put together, whether you measure by SLOC or program structure.

Note that none of this has anything to do with Mac vs PC. Passmark is simply a bad benchmark that should not be used, period. That said, there are a bunch of warning signs that PassMark's ports to everything outside its native x86 Windows are probably quite sloppy, so it's even less useful for crossplatform comparisons.

Geekbench correlates with SPEC, the industry standard in CPU benchmark and what enterprise companies such as AWS uses to judge a CPU performance. It has .99 correlation.

https://medium.com/silicon-reimagined/performance-delivered-...

Passmark is an outdated benchmark that isn't updated to use ARM instructions.

Well, no, right?

The M4 Max had great, I would argue the best at time of release, single core results on Geekbench.

That is a different claim from M4 line has the top single thread performance in the world.

I'm curious:

You're signalling both that you understand the fundamental tradeoff ("Apple doesn't make server-grade CPUs") and that you are talking about something else (follow-up with M4 family has top single-thread performance)

What drives that? What's the other thing you're hoping to communicate?

If you are worried that if you leave it at "Apple doesn't make server-grade CPUs", that people will think M4s aren't as great as they are, this is a technical-enough audience, I think we'll understand :) It doesn't come across as denigrating the M-series, but as understanding a fundamental, physically-based, tradeoff.

Maybe it is, maybe not, UNIX and Windows server software have been multithreaded / multi-process for decades, we want tons of threads and processes, not a single one.

It also include gaming machines. Of course, Apple also don't make those.

> tdp wattage vs performance x-y plot

This?

https://www.videocardbenchmark.net/power_performance.html#sc...

That’s GPUs, not CPUs

Same. I'm not sure what to make of the various claims. I personally defer to this table in general: https://www.cpubenchmark.net/power_performance.html.

I'm not sure how those benchmarks translate to common real world use cases.

If I read this right, the r8g.48xlarge at AMZN [1] has 192 cores and 1536GB which exceeds the M3 Ultra in some metrics.

It reminds me of the 1990s when my old school was using Sun machines based on the 68k series and later SPARC and we were blown away with the toaster-sized HP PA RISC machine that was used for student work for all the CS classes.

Then Linux came out and it was clear the 386 trashed them all in terms of value and as we got the 486 and 586 and further generations, the Intel architecture trashed them in every respect.

The story then was that Intel was making more parts than anybody else so nobody else could afford to keep up the investment.

The same is happening with parts for phones and TSMC's manufacturing dominance -- and today with chiplets you can build up things like the M3 Ultra out of smaller parts.

[1] https://aws.amazon.com/ec2/instance-types/r8g/

It seems Graviton 4 CPUs have 12-channels of DDR5-5600 i.e 540GB/s main memory bandwidth for the CPU to use. M3 Ultra has 64-channels of LPDDR5-6400 i.e. ~800GB/s of memory bandwidth for the CPU or the GPU to use. So the M3 Ultra has way fewer (CPU) cores, but way more memory bandwidth. Depends what you're doing.

In fairness, the sun and dec boxes I used back then (up to about 1999) could hold their own against intel machines.

Then, one day, we built a 5 machine amd athlon xp linux cluster for $2000 ($400/machine) that beat all the unix and windows server hardware by at least 10x on $/perf.

It’s nice that we have more than one viable cpu vendor these days, though it seems like there’s only one viable fab company.

In 1998-1999 I had a DEC Alpha on my desktop that was really impressive, it was a 64-bit machine a few years before you could get a 64-bit Athlon.

Yeah.

For what we needed, five 32 bit address spaces was enough DRAM. The individual CPU parts were way more than 20% as fast, and the 100Mbit switch was good enough.

(The data basically fit in ram, so network transport time to load a machine was bounded by 4GiB / 8MiB / sec = 500 seconds. Also, the hard disks weren’t much faster than network back then.)

The Alpha architecture was 64-bit from the very beginning (though the amount of addressable virtual memory and physical memory depends on the processor implementation).

I think it goes something like:

  - 2106x/EV4: 34-bit physical, 43-bit virtual
  - 21164/EV5: 40-bit physical, 43-bit virtual
  - 21264/EV6: 44-bit physical, 48-bit virtual

The EV6 is a bit quirky as it is 43-bit by default, but can use 48-bits when I_CTL<VA_48> or VA_CTL<VA_48> is set. (the distinction of the registers is for each access type, i.e: instruction fetch versus data load/store)

The 21364/EV7 likely has the same characteristics as EV6, but the hardware reference manual seems to have been lost to time...

My understanding is that the VAX from Digital was the mother of all "32-bit" architectures to replace the dead end PDP-11 (had a 64kbyte user space so wasn't really that much better than an Apple ][) and PDP-10/20 (36-bit words were awkward after the 8-bit byte took over the industry) The 68k and 386 protected mode were imitations of the VAX.

Digital struggled with the microprocessor transition because they didn't want to kill their cash cow minicomputers with microcomputer-based replacements. They went with the 64-bit Alpha because they wanted to rule the high end in the CMOS age. And they did, for a little while. But the mass market caught up.

Sounds about right.

VMS is the only OS (that I know of) that uses all 4 processor privilege modes.

Side note: The 21064 has such bizarre IPR mappings, the read values have lots of bits scrambled around compared to their write counterparts. This is likely a hardware design decision affecting the programmer's model, if I had to guess.

In 1998 I somehow got my hands on a DEC OEM 21164 533mhz board for cheap. PCs were nowhere near the performance of that at the time. It mounted in a regular PC case. A friend helped me get the power supply working (there was I think one wire to solder somewhere). Equipped with an ASUS SCSI card, an DEC Ethernet card, and an Elsa GLoria Synergy, it was a full machine. I ran Digital Unix at home on my desk on that for quite a few years. Wish I had kept it for old times sake.

One thing I remember about Alpha though was how bad the output from gcc was. Then DEC released a version of their own compilers that was command line compatible with gcc. That changed everything for open source stuff.

Asahi is a thing. For headless usage it’s pretty much ready to go already.

M3 support in Asahi is still heavily WIP. I think it doesn't even have display support, Ethernet, or Wifi yet, I think it's only serial over USB . Without any GPU or ANE support, it's not very useful for AI stuff. https://asahilinux.org/docs/M3-Series-Feature-Support/

Hmm, this page links to an out-of-tree ANE module (same as on M1/M2 I believe). No GPU support is a bummer, though.

On the other hand, you can do without display support if you’re only using it as a server. And I think USB Ethernet dongles might work for the time being?

The Asahi maintainer resigned recently. What that means for the future only time will tell. I probably wouldn't want to make a big investment in it right now.

Your wording makes it sound like it was a one-man show. Asahi has a really strong contributor base, new leadership[1], and the backing of Fedora via the Asahi Fedora Remix. While Hector resigning is a loss, I don't think it's a death knell for the project.

[1]: https://asahilinux.org/2025/02/passing-the-torch/

He was the lead developer and very prominent figure. I think it probably boils down to funding the new developments.

it was pretty close to a one man show

By what grounds do you make this statement?

My understanding is there are dozens of people working on it.

e: I'm removing this comment because on reflection I think it is probably some form of doxxing and being right on the internet isn't that important.

You believe that Hector Martin is also Asahi Lina?

https://bsky.app/profile/lina.yt

https://github.com/AsahiLina

yes, i do. if that's not true, i will certainly concede it's not a one person show

my understanding was this was an open secret though, seems pretty obvious to anyone with technical knowhow who watches their videos

I thought this was confirmed a couple years ago.

Regardless of whether this is true, there is a lot of other Asahi developers. This fact alone is immaterial.

You make it sound like there was only one.

It’s only a thing for the M1. Asahi is a Sisyphean effort to keep up with new hardware and the outlook is pretty grim at the moment.

Apple’s whole m.o. is to take FOSS software, repackage it and sell it. They don’t want people using it directly.

Not at all for M3 or M4. Support is for M2 and M1 currently.

What about serviceability? These come with soldered in ssd? That would be an issue for server use, Its too expensive to throw it away all for a broken ssd.

No, the SSD isn't soldered, it has got one or two removable modules: https://everymac.com/systems/apple/mac-studio/mac-studio-faq...

Nah, in many businesses, everything is on a schedule. For desktop computers, a common cycle is 4 years. For servers, maybe a little longer, but not by much. After that date arrives, it’s liquidate everything and rebuild.

Having things consistently work is much cheaper than down days caused by your ancient equipment. Apple’s SSDs will make it to 5 years no problem - and more likely, 10-15 years.

At my last N jobs, companies built high end server farms and carefully specced all the hardware. Then they looked at SSD specs and said “these are all fine”.

Fast forward 2 years: The $50-$250K machines have a 100% drive failure rate, and some poor bastard has to fly from data center to data center to swap the $60 drive for a $120 one, then re-rack and re-image each machine.

Anyway, soldering a decent SSD to the motherboard board would actually improve reliability at all those places.

What does soldering it to the board have to do with reliability?

If they were soldered onto those systems you talk about, all those would have had to be replaced instead of just having the drive swapped out and re-imaged.

I think the implication was that a soldered SSD doesn't give the customer as much chance to pick the wrong SSD. But it's still possible for the customer to have a different use case in mind than the OEM did when the OEM is picking what SSD to include.

It wouldn't solve other mismatched expectations. For example, the vendor might ship those SSDs only to store firmware-initiated crash dumps. They don't expect them to be used to meet production storage requirements. Maybe to occasionally boot a maintenance system, but that's it. To them, this is kind of obvious because everybody has a SAN anyway. But of course, this is not actually true in practice because customers vary a bit.

What company was specc'ing out a 6 figure machine just to put in a consumer class SSD?

Yea ive been thinking about this for a few years. The Mx series’s chip would sell into data centers like crazy if apple went after that market. Especially if they created a server tuned chip. It could probably be their 2nd biggest product line behind the iphone. The performance and efficiency is awesome. I guess it would be meat to see some web serving and database benchmarks to really know.

TSMC couldn’t make enough at the leading node in addition to all the iPhone chips Apple has to sell. There’s a physical thoughput limit. That’s why this isn’t M4.

Doesn't MacOS support these things? I'm sure Apple runs these on their datacenters somehow?

> The CPUs have zero competition in terms of speed, memory bandwidth.

Maybe not at the same power consumption, but I'm sure mid-range Xeons and EPYCs mop the floor with the M3 Ultra in CPU performance. What the M3 Ultra has that nobody else comes close is a decent GPU near a pool of half a terabyte of RAM.

Apple does not make server CPUs, they make consumer low W CPUs, it's very different.

FYI Apple runs Linux in their DC, so no Apple hardware in their own servers.

> Apple does not make server CPUs, they make consumer low W CPUs, it's very different.

This is silly. Given the performance per watt, the M series would be great in a data center. As you all know, electricity for running the servers and cooling for the servers are the two biggest ongoing costs for a data center; the M series requires less power and runs more efficiently than the average Intel or AMD-based server.

> FYI Apple runs Linux in their DC, so no Apple hardware in their own servers.

That's certainly no longer the case. Apple announced their Private Cloud Compute [1] initiative—Apple designed servers running Apple Silicon to support Apple Intelligence functions that can't run on-device.

BTW, Apple just announced a $500 billion investment [2] in US-based manufacturing, including a 250,000 square foot facility to make servers. Yes, these will obviously be for their Private Cloud Compute servers… but it doesn't have to be only for that purpose.

From the press release:

As part of its new U.S. investments, Apple will work with manufacturing partners to begin production of servers in Houston later this year. A 250,000-square-foot server manufacturing facility, slated to open in 2026, will create thousands of jobs.

Previously manufactured outside the U.S., the servers that will soon be assembled in Houston play a key role in powering Apple Intelligence, and are the foundation of Private Cloud Compute, which combines powerful AI processing with the most advanced security architecture ever deployed at scale for AI cloud computing. The servers bring together years of R&D by Apple engineers, and deliver the industry-leading security and performance of Apple silicon to the data center.

Teams at Apple designed the servers to be incredibly energy efficient, reducing the energy demands of Apple data centers — which already run on 100 percent renewable energy. As Apple brings Apple Intelligence to customers across the U.S., it also plans to continue expanding data center capacity in North Carolina, Iowa, Oregon, Arizona, and Nevada.

[1]: https://security.apple.com/blog/private-cloud-compute/

[2]: https://www.apple.com/newsroom/2025/02/apple-will-spend-more...

The interesting difference between x86 and ARM is security, not performance, btw.

Hardly. x86 and ARM follow similar security underpinnings and outcomes. ARM has TrustZone, x86 has TEEs. I cannot think of a single attack demonstrated on x86 and not on ARM or vice versa. Could you please cite one?

Who cares about TrustZone? x86 doesn't have PAC or MTE.

ARM/IoT community: https://community.arm.com/support-forums/f/architectures-and... https://community.arm.com/arm-community-blogs/b/internet-of-...

Security practitioners and academics: https://github.com/enovella/TEE-reversing/ https://media.ccc.de/v/36c3-10859-trustzone-m_eh_breaking_ar... https://www.blackhat.com/docs/us-15/materials/us-15-Shen-Att... https://i.blackhat.com/USA-19/Thursday/us-19-Peterlin-Breaki...

Sorry you could not cite an attack demonstrated on x86 and not on ARM or vice versa. Well, maybe TikTag (https://github.com/compsec-snu/tiktag) was demonstrated against ARM MTE, since you mention, and Pacman (https://pacmanattack.com/) against PAC. I was hoping for an actual response, no offense.

Is it impossible to use macOS as a virtualization host?

I think it's interesting everyone that dissented mentioned power consumption.

Our business "only" sees about 1,000-25,000 req/min, our message brokers transmit MAX 25k msg/s. Easily handled by a rack of 10 servers for redundancy.

We are not Google and we don't pretend to be, so we don't care about power, as the difference is a few dollars a month.