iPad Pro iPad Pro M4 13" sensitive to cables

[transmaster]

I have a rather large stash of cabless. Every Kind of USB cable, serial cables, VGA, DVI, lightning, Thunderbolt, etc etc. I am noticing that my new iPad pro is sensitive to the cable I am using. They sync up OK it is the charging part that is the problem. I pulled out a brand new USB "A" to 90º "C" The "A" side was blue indicating at least a 3.0 USB. I plugged it into the Anker charger I have by the bed. I have the iPad set to the 80% charge limit. The charge state at the time was 69%. After several hours of charging it seemed be stuck on 78%. I looked at the charge rate number on the Anker and it was charging at 2 Watts. I plugged in a Anker "C" to "C" I was also using and it immediately jumped to 22 Watts. This at least solved the problem I had with charging when I first started to use this sweet machine. With my old 2013 iPad Air it was the opposite trouble it would charge but not sync. There was still a lot a garbage lightning cables at the time. This bad cable was one that was supplied with cheap mechanical keyboard. I never used it.

 

[steve123]

The USB A does not support USB PD. So, you are limited to 5V at 500mA charging rate when using that with a USB 2 port and 5V at 900mA when plugged into a USB 3.1 port. The Anker USB C cable allows your USB PD charger to negotiate a higher charging voltage and current.

 

[Digitalguy]

With UBS A 3 iPads draws around 7.5w (measured). USB A can get double that via quick charge but iPads do not support quick charge. So the only way is to use PD via USB C

 

[transmaster]

Thanks, I have a bunch of old USB cables to recycle. I am thinking of replacing them with USB-4's. I know the iPad cannot do USB-4 or thunderbolt but if I have to have just one cable.

 

[steve123]

. I know the iPad cannot do USB-4 or thunderbolt but if I have to have just one cable.

The M4 iPad Pro supports TB and USB PD. So, you can get up to 40 Gbps data transfer with the new iPad and the proper cable. Note, the cable included with the iPad is only a charging cable, you need to purchase a proper TB cable separately to achieve 40 Gbps.

 

[Digitalguy]

The M4 iPad Pro supports TB and USB PD. So, you can get up to 40 Gbps data transfer with the new iPad and the proper cable. Note, the cable included with the iPad is only a charging cable, you need to purchase a proper TB cable separately to achieve 40 Gbps.

40Gbps are not just for data transfer, data transfer on TB peaks at 22.5Gbps or around 2.8GB/s
On iPad it's way less than that, I cannot even reach 1GB/s with a TB drive, while I can on MacOS and Windows.

 

[steve123]

40Gbps are not just for data transfer, data transfer on TB peaks at 22.5Gbps or around 2.8GB/s
On iPad it's way less than that, I cannot even reach 1GB/s with a TB drive, while I can on MacOS and Windows.

The port on the M4 iPad Pro is a true Thunderbolt port (unlike the Air which has a USB 3.1 Gen 2 port). For a connected SSD macOS and iOS enumerates the TB port as a PCIe gen 3 x 4 tunnel operating at about 32 Gbps.

I connected a INDEM TB3 SSD enclosure with a Samsung 980PRO NVMe SSD to my wife's M4 11 inch Pro and the DiskIO utility reports about 2000 MB/s write and 3800 MB/s read. I did not play around with the Test Size or the Chunk Size. For comparison, on my 5th Gen M1 iPad Air data transfer speed is about 500 MB/s read and write which corresponds to USB 3.1 Gen 1 speed of 5 Gbps which appears to be about half of what it should be (USB 3.1 Gen 2 = 10 Gbps). On my 16" M2Max MBP Blackmagic speedtest typically reports about 2800 MB/s read and write.

 

[Digitalguy]

DiskIO is totally unreliable with external drives... I tested a gen 2 drive and it gave me 8000 MB/s write and 300 MB/s read repeatedly... It has no clue.
I think Apple does allow apps to properly test external drives' speed on iPad.
By the way Thunderbolt maxes out at around 2800 MB/s as I said (because the actual data transfer bandwith of TB is 22.5, not 32 or 40, which is the total bandwidth, including video etc), so anything over 3000 is pure BS.
I have done my own tests (980pro in TB enclosure too) with large files and the results are what I said. The TB connection on iPad doesn't even get to gen 2 speed.
Having said that the port is true TB, as it works with TB only devices, it's just that iPadOS cannot get the full speed, not even close.

 

[steve123]

By the way Thunderbolt maxes out at around 2800 MB/s as I said (because the actual data transfer bandwith of TB is 22.5, not 32 or 40, which is the total bandwidth, including video etc), so anything over 3000 is pure BS.

TB 3 and 4 can tunnel PCIe gen 3 x 4 at 32 Gbps. You can confirm this by opening your System Information panel on a mac and inspecting your PCI devices. You will see that macOS configures the port to tunnel PCIe. You will also see how that tunnel is configured depending on the number of PCIe lanes your connected device supports. Most JHL7440 SSD enclosures use all four lanes for the NVMe controller.

My TB SSD enclosure uses an Intel JHL7440 and my tests confirm close to 2900 MB/s. Many of the newer enclosures using the new ASMedia ASM2464PD controller are reporting speeds of 3100 MB/s.

I have done my own tests (980pro in TB enclosure too) with large files and the results are what I said. The TB connection on iPad doesn't even get to gen 2 speed.

Depends on the iPad. The Mx iPad Airs only support USB 3.1 Gen 2. As far as I can tell, this is a software limitation imposed by Apple Since the TB hardware is already included with the Mx. The M4's in the new 2024 iPad Pro have a TB controller that natively supports TB 4 and Apple chooses to support TB for the Pro series. The TB 3 and 4 specifications makes support for PCIe tunnelling mandatory. If a vendor marks a port as a Thunderbolt port on a device then it must comply with the TB specification. Apple chooses to mark the port on the iPad Air as USB C and the port on the iPad Pro as Thunderbolt. Some computers with USB 4 do not include the PCIe tunnelling so they cannot achieve the higher speed and are not TB compatible.

 

[transmaster]

I purchased several Anker Thunderbolt cables, and one expensive Apple Thunderbolt cable. So for now I a good to go cable wise learning about the possible charge rates with the older USB cables I have was really good info.

 

[steve123]

I purchased several Anker Thunderbolt cables, and one expensive Apple Thunderbolt cable. So for now I a good to go cable wise learning about the possible charge rates with the older USB cables I have was really good info.

There are two types of Thunderbolt cables. Passive and active. All TB cables have a PD chip for power delivery compliance. The passive cables are less expensive and are less than 1m length because anything longer degrades the signal integrity of the data. The active cables have adaptive equalization of the data that maintains signal integrity over longer distances. The thing to keep in mind is that anything longer than 1m should be an active cable if you want to achieve reliable high speed communication. Active cables are more expensive than passive cables.

 

[Digitalguy]

TB 3 and 4 can tunnel PCIe gen 3 x 4 at 32 Gbps. You can confirm this by opening your System Information panel on a mac and inspecting your PCI devices. You will see that macOS configures the port to tunnel PCIe. You will also see how that tunnel is configured depending on the number of PCIe lanes your connected device supports. Most JHL7440 SSD enclosures use all four lanes for the NVMe controller.

My TB SSD enclosure uses an Intel JHL7440 and my tests confirm close to 2900 MB/s. Many of the newer enclosures using the new ASMedia ASM2464PD controller are reporting speeds of 3100 MB/s.



Depends on the iPad. The Mx iPad Airs only support USB 3.1 Gen 2. As far as I can tell, this is a software limitation imposed by Apple Since the TB hardware is already included with the Mx. The M4's in the new 2024 iPad Pro have a TB controller that natively supports TB 4 and Apple chooses to support TB for the Pro series. The TB 3 and 4 specifications makes support for PCIe tunnelling mandatory. If a vendor marks a port as a Thunderbolt port on a device then it must comply with the TB specification. Apple chooses to mark the port on the iPad Air as USB C and the port on the iPad Pro as Thunderbolt. Some computers with USB 4 do not include the PCIe tunnelling so they cannot achieve the higher speed and are not TB compatible.

Good if some new enclosures can do a bit better than what has been possible so far.... with MacOS and Windows.
That doesn't change the fact that we are very far from it on iPads and that the data spit out by DiskIO is pure BS.
I did my tests with the M1 iPad pro in my signature.
At this point the only real advantage of TB on iPad is that it works with TB only devices (that cannot fall back on USB C). Will it be better on M4? I don't know, I don't have M4 so I can only speak for M1, whose speeds are a fraction of what they are on MacOS so far.

 

[transmaster]

Just purchased 2 more Anker Intel Certified Thunderbolt 4 2.3 foot cables.

 

[transmaster]

One of the things I really like about the Intel certified TB-4 is the built in firewall they have

 

[steve123]

the data spit out by DiskIO is pure BS

I am suspicious of some of the data, particularly the read speed. I think caching maybe a factor in that number. The write speed looks reasonable but may suggest Apple is only using 2 lanes of PCI or else iPadOS has some serious IO bottlenecks that interfere.

i downloaded Jazz Disk Speed and used that. Results appear to be more reliable. The first screenshot is the internal SSD. The second screenshot is the external TB connected SSD. For the external SSD, read speed looks close to expected and writes seem to be slower than expected.

 

[Digitalguy]

I am suspicious of some of the data, particularly the read speed. I think caching maybe a factor in that number. The write speed looks reasonable but may suggest Apple is only using 2 lanes of PCI or else iPadOS has some serious IO bottlenecks that interfere.

i downloaded Jazz Disk Speed and used that. Results appear to be more reliable. The first screenshot is the internal SSD. The second screenshot is the external TB connected SSD. For the external SSD, read speed looks close to expected and writes seem to be slower than expected.

View attachment 2388223 View attachment 2388224

Tried it, got similar results with my 980 pro 1tb (little slower read, little faster write).
I don't know if it's reliable but it does not match my own transfer tests. I will do more tests in the future when I have some time, to see if things have improved (I did my tests last year, hopefully things have improved in the meantime)