Mac Mini M4 Pro Thunderbolt 5 speed issues.

I plugged in my Sandisk Professional G40 Thunderbolt 3 compatible SS into the Thunderbolt 5 ports on my new Mac mini M4 Pro machine, and the speeds are much slower than advertised. I am only getting about 800-900MB read and write speeds, and I should be getting 2500-2700 Read and write. I tested the drive on my MacBook Air M1 and am getting those speeds. The M1 is reading the drive like a PCI express drive. The Mac Mini M4 Pro reads the drive like a USB drive that gets 10gbs speed. I am using the TB3 cable that comes with the SSD, and I also tried it with an older Apple Thunderbolt 3 cable, and I am getting the same speeds on both machines. So, I know it is not the cable. It is something internal with the new TB 5 connection. It shows the 120gbs of the system information on the computer. If I get a TB4 or five cables, will that fix the issue? Any help would be greatly appreciated. I need to return this drive if I can not get it to work.

Mac mini, macOS 15.2

Posted on Dec 13, 2024 11:14 AM

Top-ranking reply

Davefilmguy Author

Level 1

16 points

Posted on Dec 15, 2024 03:40 PM

I may have figured out the issue. I went through Apple support, and they had me reinstall the OS and try the drive. When the computer finally rebooted and came back up, I only had 1 of my two monitors, the one plugged into the HDMI. The other monitor was using USBC on one of the TB5 ports. All this to say: When I tested the drive with just one monitor plugged in, I got faster speeds. Then I restarted the computer, made sure the other monitor was plugged into the TB5 port, and did the test again. I got slower speeds again on the drive. Then, I unplugged the monitor from the TB5 port and switched it out to an HDMI cable. I plugged that into a USBC hub I was using on one of the other TB5 ports and got faster speeds again. So, Apple has an issue with having all three ports utilized simultaneously. I am still in talks with Apple support about this. Unplug other devices from the back and try the SSD speed again after restart.

View in context

Mac Mini M4 Pro Thunderbolt 5 speed issues.

Similar questions