New M4 Max Mac Studio - Thunderbolt 5 ports issues - help

[impatient2]

Need some help Please:

I picked up my new M4 Max Mac Studio 2 days ago from a local Apple Store. It's a standard config, except I updated to the 1TB SSD.

I seem to be having issues with the 4 Thunderbolt ports on the back on the unit, with all 4 ports not recognizing devices at the same time. It seems like it might be a power issue?

Not sure how many watts the 4 ports combined can support. Even Apple was unable to tell me. Spent about 4 hours on the phone with their tech support yesterday, they couldn’t resolve & finally had to bring it in today to the Apple Store where I picked it up & had one of the Specialists look at it.

I'm using 2 Dell 27" S2725DS 27" 2K monitors. 1 Plugged into the Studio’s HDMI port, the other plugged into 1 of the Thunderbolt 5 ports on the back via a DisplayPort to USB-C Cable adapter.

I’m also trying to use 3 external SSDs. All 3 are Acasis enclosures each with a 2TB SSD inside:

- Acasis TB501 Pro Thunderbolt 5 with 2TB WD SN850X SSD
- Acasis TBU405 Air Thunderbolt 4 with Inland Performance Plus 2TB PCIe Gen 4 x4 NVMe M.2 SSD (Micro Center House Brand) Purchased 3/17/25
- Acasis TBU405 Air Thunderbolt 4 with Inland TN470 2TB PCIe Gen 4 x4 NVMe M.2 SSD (Micro Center House Brand).

When I bought the Studio into the Apple Store today, the Specialist connected 2 monitors (1 with HDMI, 1 via Thunderbolt 5 port using above mentioned DisplayPort to USB-C adapter cable) and also all 3 of my external drives/enclosures mentioned above.
One of the drives we found had a defective 1TB drive inside at the time, so we unplugged it & the Specialist replaced it with an external orange Lacie drive of some kind. At that time, with my Acasis TB501, TBU405 Air, Lacie orange drive & both monitors plugged in, all 4 USB-C/Thunderbolt 5 ports were recognizing those devices. We even rebooted the Studio to make sure they were still recognized upon reboot & they were. I thought my problems were solved.

Now, when I got home today from the Apple Store visit with the Specialist, I plugged in all 3 Acasis drives mentioned above + both Dell monitors (1 via Thunderbolt 5), & the Studio is only seeing 2 of my external drives – the TB501 Pro & 1 of the TBU405 Airs on the Desktop, Finder, & System Info > Thunderbolt/USB4 section. Same issue I was having when I called Apple Tech Support Yesterday.

I unplugged the monitor from the Thunderbolt 5 port, rebooted, & all 3 Acasis drives show on the Desktop, Finder & System Info. I’m able to copy an empty folder between all 3 external drives, no issues. Rebooted & all 3 drives still show up.

Now I plug in the monitor into the Thunderbolt 5 port again. All 3 drives still show up on the desktop. Still able to copy the empty folder between all 3 drives back & forth.

However, Reboot with both monitors plugged in & all 3 drives: again only 2 of the external drives show up on the Desktop, Finder, & System Info. When I try unplugging the drive that doesn’t show up & plug it back in, I get a pop-up message saying “Accessory needs more Power. Disconnecting other accessories may allow this to work.

I’m at my wits end with this, considering just returning the Mac Studio & maybe buying another one later in hopes I get a units that can actually recognize & use the 4 devices I’m trying to use on the 4 Thunderbolt 5 ports.

Appreciate any ideas help.

Love the speeds of the computer, macOS of course, but thinking I got a lemon?

I also tried posting this on the Apple Community support forum, but for some reason, I can’t log into the site on any browser & don’t have any issues with any other website, including Apple.com.

Thanks.

 

[Sarpanch]

It’s a well known issue for Apple desktops. Despite Apple advertising them as Thunderbolt 4/5, they don’t always meet the power requirements of supplying 15W to external unpowered devices. I have a M4 Mac Mini and a M4 Max Mac Studio, and they can only power 2 external Thunderbolt drives. All 3 of my drives are Thunderbolt only (like your Acasis Air model). Some Acasis enclosures have a USB fall-back option and will connect at USB 3.1 Gen 2 speeds when there is not enough power. I suppose the Lacie drive in the Apple store was a 3.1 Gen 2 device, which is why it connected.

More information in this thread here ->
'M4 Mac Mini - External Thunderbolt Drives Limitation'
https://forums.macrumors.com/threads/m4-mac-mini-external-thunderbolt-drives-limitation.2445812/

 

[Norbert Mikołajczyk]

What a disappointment in regards of Mac mini with only 3 tb ports.
So no matter if you have mini or studio in the end you need a self powered thunderbolt hub to be able to connect more thunderbolt drives…

 

[Velin]

A powered T-5 hub should fix this easily. There are several available. I imagine it will solve all your issues and run great. I run Acasis enclosures too with a Studio, they are rock solid and so is the Studio.

Also, this is not an Apple-only issue. Over in PC land, let me tell you, some of the motherboards and I/O controllers/bus are absolutely atrocious. Troubleshooting is difficult, given all the different configurations, mobo firmware updates, chipset drivers, and on and on. On a PC, try connecting a bunch of unpowered drives to both the rear I/O and the PC case I/O, and watch the problems multiply like weeds. (Though, in fairness, with a PC there usually are multiple NMV2 ports so you can run three or even four SSD internally at lightning-fast speeds.)

 

[OldMike]

I've been booting Macs from external drives since the early 2000s. I leave my computers running 24/7 and never had issues with disconnects. When I replaced my M2 Pro Mac Mini with a M4 Mac Mini I had nothing but problems. Continuous disconnects until I attached my drives to a powered thunderbolt hub.

This has been running pretty smoothly for a few months, but I did get a surprise disconnect a couple of weeks ago. I was thinking there was something wrong with my M4 Mini, but saw others were having similar issues trying to run an external drive off of M4 Minis. Again, my M2 Pro never had an issue with the same setup.

I've been waiting for some more reviews/benchmarks to come out and then I was planning to pick up a new Mac Studio. My last M1 Max Mac Studio ran off of external without a single issue. I was really hoping that the new Mac Studio wouldn't have this same issue - but this thread has me a little concerned now.

To me, it seems like this issue is more prevalent with the M4 Macs. I'm wondering if this is a known issue with M4 Macs, and if perhaps the M3 Ultra Mac Studio might not have this same issue? Does anyone have insight on if this might be the case?

@impatient2 I hope you get this worked out with your Mac Studio. With 4 or 6 TB5 ports, it is a shame if we still need to run a powered hub with the Mac Studio in order to get a few external NVMe drives going.

 

[Chancha]

Studio Ultra - Simultaneous use of Bus Powered TB devices limited? (title edited)

Today I discovered that I cannot connect more then three thunderbolt drives (and the BenQ display using USBC) to my Studio Ultra. On the back four ports, I have connected: 1. BenQ SW321C 2. ProGrade TB3 CF Express card reader 3. & 4. Orico TB4 enclosure w/Samsung 980 Pro NVMe SSD If I connect...

forums.macrumors.com

More in depth threads have discussed the issue on the forum, such as the one above.

TL;DR: yes there is a finite pool of power, but by shuffling the order of which the devices are plugged in you can release and re-arrange that:

1) unplug everything
2) only plug the most power hungry devices first, namely NVMe SSD enclosures
3) if possible, use USB4 not Thunderbolt, on a device that can do both such as the Acasis TBU-405
4) plug the low power devices last, including ones that supposedly takes no power like displays

In general there is a limit of 2 "max power draw" devices, the 3rd one will need to be relegated to an external powered dock for instance.

Yes, it is a very annoying, undocumented issue with all Apple Silicon Macs. I am not sure about the Mac Pro but I guess it shares the same logic, despite having a beefy PSU.

 

[impatient2]

Thanks to everyone for their replies & info.
I've decided to keep the Studio & just deal with the Thunderbolt issues.

Today, I ordered the OWC Thunderbolt 5 hub off Amazon, to hopefully allow me to connect all 3 Acasis Thunderbolt enclosures/2TB drives along with my 2nd Dell monitor.

I'll reply back once I get the hub & let everyone know how it goes.

Experienced a strange issue just a few minutes ago for the 2nd time today: I installed Sequoia onto the TB501 Pro Thunderbolt 5 with 2TB WD SN850X SSD earlier today & have been booting off of it. I just powered up to reply here & all of a sudden, my monitor/display lost video signal. This is the monitor that's plugged into the HDMI port. The other monitor is currently unplugged as I wait for the OWC TB 5 hub. I don't think this was a video issue though. I get the sneaky suspicion that this was related to a connection loss with the TB501 Pro running Sequoia. So I booted off the Studio's internal SSD to post this reply.

Ugh, Apple. If only your internal storage was affordable, I'd have at least 4TB SSD built in.

Another thought: If the OWC hub runs well, maybe I'll RAID 0 the TBU405 Air drives. Has anyone here tried it with external TB drives? Results?

 

[Norbert Mikołajczyk]

Thanks to everyone for their replies & info.
I've decided to keep the Studio & just deal with the Thunderbolt issues.

Today, I ordered the OWC Thunderbolt 5 hub off Amazon, to hopefully allow me to connect all 3 Acasis Thunderbolt enclosures/2TB drives along with my 2nd Dell monitor.

I'll reply back once I get the hub & let everyone know how it goes.

Experienced a strange issue just a few minutes ago for the 2nd time today: I installed Sequoia onto the TB501 Pro Thunderbolt 5 with 2TB WD SN850X SSD earlier today & have been booting off of it. I just powered up to reply here & all of a sudden, my monitor/display lost video signal. This is the monitor that's plugged into the HDMI port. The other monitor is currently unplugged as I wait for the OWC TB 5 hub. I don't think this was a video issue though. I get the sneaky suspicion that this was related to a connection loss with the TB501 Pro running Sequoia. So I booted off the Studio's internal SSD to post this reply.

Ugh, Apple. If only your internal storage was affordable, I'd have at least 4TB SSD built in.

Another thought: If the OWC hub runs well, maybe I'll RAID 0 the TBU405 Air drives. Has anyone here tried it with external TB drives? Results?

Yeah, someone tested it in RAID:

About connecting drives to external hub - if you aim for the best performance and plan to transfer big set of files between the drives then connecting them all to the same hub will create bottleneck.
So the best option will be connecting 2 drives to Mac tb5 ports and one drive to the self powered hub.

 

[khollister]

Curious why you feel you have to boot from a 2TB external rather than the 1TB internal? I have a LOT of apps installed including Cubase & Logic which want to put their factory plugins/sounds etc into /Library, and I am still just under 400GB for my boot drive. Of course my working files (photography & music related) are stored on an external (OWC 1M2 USB4 with a WD SN540X 8TB).

I realize it is more $ but you could greatly simplify your setup and possibly eliminate the nee for the hub by putting a 8TB blade in the TB5 enclosure and calling it a day (wouldn't need the TB4 devices and you would dodge the power management issue).

FYI the 1M2 USB4 enclosures use less power than TB and I can run 3 directly from my Studio. The speed is slightly faster than a TB3/4 drive (3000 MBs vs 2800). I have 4 of them and couldn't be happier - no fans, blades run fairly cool, never any weird disconnects or other funny business and they aesthetically fit in with the Studio as they are natural aluminum color.

 

[Norbert Mikołajczyk]

Curious why you feel you have to boot from a 2TB external rather than the 1TB internal? I have a LOT of apps installed including Cubase & Logic which want to put their factory plugins/sounds etc into /Library, and I am still just under 400GB for my boot drive. Of course my working files (photography & music related) are stored on an external (OWC 1M2 USB4 with a WD SN540X 8TB).

I realize it is more $ but you could greatly simplify your setup and possibly eliminate the nee for the hub by putting a 8TB blade in the TB5 enclosure and calling it a day (wouldn't need the TB4 devices and you would dodge the power management issue).

FYI the 1M2 USB4 enclosures use less power than TB and I can run 3 directly from my Studio. The speed is slightly faster than a TB3/4 drive (3000 MBs vs 2800). I have 4 of them and couldn't be happier - no fans, blades run fairly cool, never any weird disconnects or other funny business and they aesthetically fit in with the Studio as they are natural aluminum color.

That and on top of that, what's wearing off the ssd is constant writes of large chunks data.
So when local ssd is loaded but the traffic is small than the health of the ssd will be fine for many, many years.
So there is no need for moving home to external.
I for example am using external nvme ssd drive for Illustrator, Photoshop, After Effects Cache, Photos etc.

 

[impatient2]

Curious why you feel you have to boot from a 2TB external rather than the 1TB internal?

Trying to keep the wear & tear on the internal SSD of the Studio to a bare minimum if possible. I also like the idea of a large 8TB external drive instead of three external 2TB SSD's, however the pickings are slim for those at my local Micro Center. Cheapest one is the WD Black SN850X for $600. Ouch.

 

[khollister]

Trying to keep the wear & tear on the internal SSD of the Studio to a bare minimum if possible. I also like the idea of a large 8TB external drive instead of three external 2TB SSD's, however the pickings are slim for those at my local Micro Center. Cheapest one is the WD Black SN850X for $600. Ouch.

The WD 8TB is a great drive, especially for $600. It runs several degrees cooler than the Inland 8TB blades I have and it is cheaper by quite a bit.

I really don't think you are going to "wear out" the internal SSD before you decide to upgrade to a new Mac. Even so, that's what Apple Care is for. The annual AC+ cost for my new M4Max is $59/year.

 

[Chancha]

If all you use are conventional software with a GUI, even intensive professional suites, you shouldn't think about wearing SSD.

I think if the purpose is to tinker or experiment like the above video claims, it is fine to move home folder to externals with symlinks. Then with software RAID-0 of two discrete bus powered drives... the additional points of failure cannot be counted by just 10 fingers. If a real workflow happens on such a volume, make sure you are 100% ready to lose all data on it any second, like only using as a scratch disk, or temp media organizing / dropping zone.

Also since above mentioned USB4; with Acasis TBU-405 that have both the JHL7440 TB controller on top of the Realtek USB4 controller, a really interesting behaviour is if they are plugged after the 2 bus-powered device limit is hit, macOS will still mount them but fallback to USB4 (or USB3 10Gbps depending if your Mac has USB4 or not). The OP's specific version of TBU-405 is the Air, which only has the TB controller so it cannot "benefit" from that fallback.

 

[hajime]

It’s a well known issue for Apple desktops. Despite Apple advertising them as Thunderbolt 4/5, they don’t always meet the power requirements of supplying 15W to external unpowered devices. I have a M4 Mac Mini and a M4 Max Mac Studio, and they can only power 2 external Thunderbolt drives. All 3 of my drives are Thunderbolt only (like your Acasis Air model). Some Acasis enclosures have a USB fall-back option and will connect at USB 3.1 Gen 2 speeds when there is not enough power. I suppose the Lacie drive in the Apple store was a 3.1 Gen 2 device, which is why it connected.

More information in this thread here ->
'M4 Mac Mini - External Thunderbolt Drives Limitation'
https://forums.macrumors.com/threads/m4-mac-mini-external-thunderbolt-drives-limitation.2445812/

How much power can each port provide on the M4 Mac mini and M4 Max Studio?

 

[Zubba]

Anybody with an M3Ultra model confirm this is also an issue with it?

 

[bxs]

Anybody with an M3Ultra model confirm this is also an issue with it?

Will have my M3 Ultra tomorrow.... so will be testing things for sure.

 

[PaulD-UK]

@hajime "How much power can each port provide on the M4 Mac mini and M4 Max Studio?"
Individually, theoretically, 5V 3A to a non-smart device...
In practice? 5.06V @ 2.48A with an M1 Max MBP...
Which seems to match experience.

I've posted on the implications that the laws of physics poses on such levels of power draw: 😉

https://forums.macrumors.com/threads/m4-mac-mini-external-thunderbolt-drives-limitation.2445812/post-33815141

 

[bxs]

I have a question related to Apple's claim for memory bandwidth.

For the M4 Max Studio the claim is 410 GB/s
For the M3 Ultra Studio the claim is 819 GB/s

My question here is.... Is this bandwidth applicable to what type...

1) memory to memory ?
or
2) CPU to/from memory ?
or
3) GPU to/from memory ?
and finally
4) Memory to/from an application's I/O buffers using direct I/O requests ?

I have a temporary M4 Pro mini with 24GB UM while waiting for my M3 Ultra Studio to show up, and Apple states it provides some 273 GB/s memory bandwidth. When I run AmorphousMemoryMark it reports

1) for reading from memory the rate is some 156 GB/s
and
2) for writing to memory some 248 GB/s

However, if I run a read and write for a file that is memory resident (it fits in its entirety within the kernel buffer cache) I'm not seeing data rates anywhere close to what AmorphousMemoryMark is displaying for the read and write.

For example, I tested using an application for reading and writing a memory resident file and the best data rate I obtained was some 11.7 GB/s. This is nowhere close to Apple's memory bandwidth/2 value of 273/2 or the AmorphousMemoryMark results of 156 GB/s for reading and some 248 GB/s for writes.

Example for reading a memory resident file using Terminal's dd command.
dd if=10GB_file of=/dev/null bs=1g count=10 oflag=direct
10+0 records in
10+0 records out
10737418240 bytes transferred in 0.915674 secs (11726245629 bytes/sec)

Thanks for any responses that can clear up this aspect....

 

[picpicmac]

For the M4 Max Studio the claim is 410 GB/s
For the M3 Ultra Studio the claim is 819 GB/s

In these cases I'm pretty confident that Apple is just using the LPDDR5 (or LPDDR5x) stated bandwidth for the chips. (Same for Nvidia, btw, and others.)

And that will be, strictly, between the LPDDR chip and it's partnered memory controller on the SoC.

The performance one will get in use will be lower because you have memory management overhead within MacOS and inside the SoC.

 

[bxs]

In these cases I'm pretty confident that Apple is just using the LPDDR5 (or LPDDR5x) stated bandwidth for the chips. (Same for Nvidia, btw, and others.)

And that will be, strictly, between the LPDDR chip and it's partnered memory controller on the SoC.

The performance one will get in use will be lower because you have memory management overhead within MacOS and inside the SoC.

I do wonder how accurate the AmorphousMemoryMark is for me to accept as being applicable for my workload?

 

[impatient2]

So, I received the OWC TB 5 doc today, hooked it up to my Studio, 3 external drives, 2 monitors, and . . . so far so good. Running nice & smooth. Both monitors & all 3 drives recognized. I have 1 monitor connected to HDMI, 1 to a TB port on the Studio with the DP to USB-C cable adapter, the TB501 Pro connected to another TB port on the Studio, and both TBU405 Air drives running off the OWC dock. The dock comes w/a power brick that's 180W & almost the same size as the dock itself. About the only thing I don't like about this setup so far is the clutter of cables, but I've tied them down & managed them as best as possible. I'll post a picture of my setup later today or tomorrow.

Now wondering if I should power off the dock when I turn off my Mac Studio, or leave it powered on? I sleep the Studio usually throughout the day when not in use, but power it off at the end of the day when I go to sleep.

 

[Chancha]

I do wonder how accurate the AmorphousMemoryMark is for me to accept as being applicable for my workload?

The advertised memory bandwidth is talking about the total potential bandwidth in counting the memory controller on die in conjunction with the number of DRAM chips, that’s why the M3 Pro reducing to 3 DRAMs got a bandwidth reduction from M2 Pro, since it went down to 3 from 4 chips. And also the binned M3 Max and M4 Max and M3 Ultras have 3/4 of their full unbinned counterparts, because it would have taken all available cores of the full chip to saturated the bandwidth potential, that the binned chips don’t have.

Tests like AmorphousMemoryMark is I think running a C library function so it is only measuring the system’s CPU side. In Apple Silicon’s unified memory way of thinking, Apple designed the whole pool of memory to be addressable by both the CPU and GPU (and perhaps also the NPU) at the same time, so in order to measure you need a test written to use all these cores at the same time, or at least run serval tests that utilize them separately at the same time.

What is your workload that it this concerned about memory performance?

 

[bxs]

So, I received the OWC TB 5 doc today, hooked it up to my Studio, 3 external drives, 2 monitors, and . . . so far so good. Running nice & smooth. Both monitors & all 3 drives recognized. I have 1 monitor connected to HDMI, 1 to a TB port on the Studio with the DP to USB-C cable adapter, the TB501 Pro connected to another TB port on the Studio, and both TBU405 Air drives running off the OWC dock. The dock comes w/a power brick that's 180W & almost the same size as the dock itself. About the only thing I don't like about this setup so far is the clutter of cables, but I've tied them down & managed them as best as possible. I'll post a picture of my setup later today or tomorrow.

Now wondering if I should power off the dock when I turn off my Mac Studio, or leave it powered on? I sleep the Studio usually throughout the day when not in use, but power it off at the end of the day when I go to sleep.

The OWC TB5 Hub has its own power button so can without any fuss be powered off. It also has the blue light indicating its connected to the host Mac.

I leave my OWC TB5 Hub powered on even with the Mac shutdown.

 

[xraydoc]

I leave my OWC TB5 Hub powered on even with the Mac shutdown.

You can shutdown a Mac?

Kidding aside, I have background things happening all the time on my Mac (HomeBridge server, AppleTV movie server off of a large external HHD, incoming email filtering and a few other things), so it never powers down and never sleeps. The displays turn themselves off after 20 minutes, but the Mac itself is on 24/7.

My new Studio has enough RAM and speed that it's replaced an old Intel Mac mini as the HomeBridge server and a different old Intel Mac as the movie server. Might even break even on the cost of the new Mac Studio in electricity usage annually, lol (not really, but still not insignificant).

Now I just need to upgrade my home's network to 10Gb.

 

[picpicmac]

M3 Ultras have 3/4 of their full unbinned counterparts

Note that the 28 CPU core M3 Ultra can still be configured with 256GB of RAM, which means it has the full 8 controllers and SDRAMs (at 32GB each.)